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Issued  August  14, 1911. 

U.  S.  DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF  ANIMAL  INDUSTRY.— BULLETIN  139. 

A.  D.  MKLVIN,  CHIBF  OF  BUREAU. 


NUTRITIVE  VALUE  OF  THE  NONPROTEIN 
OF  FEEDING  STUFFS. 


BY 


HENRY  PRENTISS  ARMSBY,  PH.  D.,  LL.  D., 

Director  of  the  Institute  of  Animal  Nutrition  of  The  Pennsylvania 

State  College;  E.\ perl  in  Animal  .\itlrition, 

Bureau  of  Animal  Industry. 


WASHINGTON: 

GOVERNMKNT    PRINTING   OFFICE. 
1911. 


Library 

Citrus  Experiment  Station 
University  ut  ulifornia 
U.  S.  DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF  ANIMAL  INDUSTRY.— BULLETIN  139. 

A.  n.  MF.LVIN,  CHIEF  OF  BUREAU. 


THE  NUTRITIVE  VALUE  OF  THE  NONPROTEIN 
OF  FEEDING  STUFFS. 


BY 


HENRY  PRENTISS  ARMSBY,  PH.  D.,  LL.  D., 

Director  of  the  Institute  of  Animal  Nutrition  of  The  Pennsylvania 

State  College;  Expert  in  Animal  Nutrition, 

Bureau  of  Animal  Industry. 


WASHINGTON: 

GOVFRNMFNT    PRINTING    OFFIOF.. 
1911. 


THE  BUREAU  OF  ANIMAL  INDUSTRY. 


Chief:  A.  D.  MELVIN. 
Assistant  Chief:  A.  M.  FARRINGTON. 
Chief  Clerk:  CHARLES  C.  CARROLL. 

Animal  Husbandry  Division:  GEORGE  M.  ROMMEL,  chief. 
Biochemic  Division:  M.  DORSET,  chief. 
Dairy  Division:  B.  H.  RAWL,  chief. 

Inspection  Division:  RICE  P.  STEDDOM,  chief;  MORRIS  WOODEN,  R.  A.  RAMSAY, 
and  ALBERT  E.  BEHNKE,  associate  chiefs. 

Pathological  Division:  JOHN  R.  MOHLER,  chief. 
Quarantine  Division:  RICHARD  W.  HICKMAN,  chief. 
Zoological  Division:  B.  H.  RANSOM,  chief. 
Experiment  Division:  E.  C.  SCHROEDER,  superintendent. 
Editor:  JAMES  M.  PICKENS. 

2 


LETTER  OF  TRANSMITTAL. 


UNITED  STATES  DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF  ANIMAL  INDUSTRY, 

Washington.,  1).  6'.,  May  8,  1911. 

SIR:  I  have  the  honor  to  transmit  herewith  a  manuscript  on  ''The 
Nutritive  Value  of  the  Nonprotein  of  Feeding  Stuffs,"  by  Dr.  Henry 
Prentiss  Armsby,  who  is  in  charge  of  the  cooperative  investigations 
in  animal  nutrition  by  this  bureau  and  the  Institute  of  Animal  Nutri- 
tion of  the  Pennsylvania  State  College.  Preliminary  to  writing  a 
paper  dealing  with  maintenance  requirements  in  feeding  animals  he 
has  found  it  necessary  to  consider  the  value  of  the  nonprotein  nitrog- 
enous substances  in  the  ration.  He  has  therefore  in  the  accom- 
panying manuscript  reviewed  the  literature  of  investigations  on  the 
latter  subject  and  summarized  the  results,  and  in  conclusion  has 
discussed  their  bearing.  I  respectfully  recommend  the  publication 
of  this  paper  as  a  bulletin  of  this  bureau. 
Respectfully, 

A.  I).  MELVIN, 

Chief  of  Bureau. 
Hon.  JAMES  WILSON, 

Secretary  of  Agriculture. 


CONTENTS. 


Page. 

Introduction 5' 

Experiments  on  carnivora 6 

Experiments  on  omnivora 12 

Experiments  on  herbivora 12 

Behavior  of  nonproteins  in  digestive  tract  of  herbivora 14 

Nutritive  value  of  nonprotein  for  herbivora 28 

Nonprotein  a  source  of  protein 28 

Effect  of  nonprotein  on  total  production 38 

Direct  utilization  of  ammonium  salts 44 

R6sum6 45 

Conclusions 46 

V?,lue  for  maintenance  of  protein  tissues 46 

Value  for  production 47 

The  computation  of  rations 47 

4 


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Citrus  Experiment  Station 
University  uf  uiifoniia 


THE  NUTRITIVE  VALUE  OF  THE  NONPROTEIN  OF 
FEEDING  STUFFS. 


INTRODUCTION. 

It  is  well  known  that  the  nitrogenous  constituents  of  feeding  stuffs 
comprise,  besides  the  true  proteins,  numerous  other  compounds  of 
the  most  varied  nature,  including  alkaloids,  nitrogenous  glucosids, 
amino  acids  and  amids,  phosphatids,  nitrates,  ammonium  salts, 
etc.,  so  that  in  the  aggregate  a  not  inconsiderable  proportion  of  the 
nitrogen  supply  of  herbivorous  animals  is  derived  from  these  sub- 
stances. All  these  diverse  nitrogenous  compounds  have  been  for 
convenience  grouped  under  the  name  "nonprotein."  The  name, 
of  course,  is  an  abbreviation  for  nonprotein  nitrogenous  matters, 
and,  as  the  foregoing  partial  enumeration  shows,  the  group  is  very 
heterogeneous  in  its  nature. 

Alkaloids  and  nitrogenous  glucosids  do  not  appear  to  be  especially 
abundant  in  the  ordinary  feeding  stuffs  of  domestic  animals,  and  where 
they  do  occur  are  distinguished  rather  by  specific  physiological  effects 
than  by  their  nutritive  value  in  the  ordinary  sense.  As  regards  the 
nutritive  value  of  the  phosphatids,  comparatively  little  is  known, 
although  it  is  claimed  that  the  lecithins  have  a  stimulating  effect 
upon  growth.  Of  all  the  groups  of  nonnitrogenous  substances  above 
enumerated,  the  amino  acids  and  amids  appear  to  be  most  abundant. 
Moreover,  they  are  of  special  interest  because  they  arc  products  of  the 
protein  metabolism  of  the  plant  and  are  to  a  considerable  extent  iden- 
tical with  the  protein  cleavage  products  which  appear  to  play  such  a 
large  role  in  animal  nutrition.  From  a  practical  standpoint,  then,  the 
question  of  the  nutritive  value  of  nonproteins  is  largely  identical 
with  that  of  the  nutritive  value  of  the  so-called  "amids."  This 
•question  is  considered  in  the  present  publication  solely  from  the  stand- 
point of  their  value  for  the  maintenance  or  production  of  body  pro- 
tein, without  reference  to  their  value  as  sources  of  energy. 

It  has  been  shown  by  physiologists  that  the  animal  undoubtedly 
has  the  power  to  build  up  body  proteins  out  of  the  comparatively 
simple  cleavage  products  resulting  from  the  digestion  of  food  proteins. 
It  is  natural  to  assume,  therefore,  that  when  similar  cleavage  products 

5 


6  NUTRITIVE   VALUE    OF    NONPROTEIN    OF    FEEDING   STUFFS. 

are  found  in  feeding  stuffs  they  are  capable  of  undergoing  the  same 
chemical  reactions  in  the  body  as  if  they  arose  from  the  digestive  cleav- 
age of  protein.  Looking  at  the  question  of  the  nutritive  value  of 
the  nonprotein  from  this  point  of  view,  it  is  apparent  that  the  ques- 
tion is  to  a  considerable  extent  similar  to  that  of  the  relative  values 
of  different  proteins.  Just  as  the  proportions  of  the  different  amino 
acids,  etc.,  yielded  by  different  proteins  vary,  so  do  the  proportions  of 
the  similar  substances  found  in  the  nonprotein  of  different  feeding 
stuffs,  while  neither  the  proportions  nor  the  specific  compounds  are 
identical  in  proteins  and  nonproteins.  Evidently,  then,  it  is  futile  to 
seek  to  establish  any  definite  ratio  between  protein  and  nonprotein  as 
to  their  value  to  the  organism,  because  both  of  them,  but  especially  the 
latter,  are  in  this  respect  more  or  less  variable  and  indefinite  concep- 
tions. The  failure  to  recognize  this  fact  is  responsible  for  not  a  little 
of  the  existing  confusion  of  thought  on  this  question.  Thus,  many  of 
the  earlier  investigations  of  the  nutritive  value  of  nonproteins  1 
were  made  upon  single  amids  or  amino  acids,  notably  on  asparagin, 
largely  because  the  latter  occurs  rather  abundantly  in  plants  and  is 
readily  obtained  reasonably  pure,  although  it  is  not  itself  a  constitu- 
ent of  the  protein  molecule.2  In  these  earlier  experiments  numerous 
investigators  showed  that  various  single  amino  acids  and  amids  are 
katabolized  in  the  animal  body,  their  nitrogen  reappearing  as  urea, 
although  Voltz  3  has  lately  claimed,  contrary  to  earlier  results  by 
Andrlik,  Velich,  and  Stanek,4  that  betain  is  an  exception.  As  regards 
their  ability  to  replace  the  protein  of  the  food,  however,  or  to  maintain 
protein  tissue,  these  experiments  indicated  a  marked  apparent  dif- 
ference between  carnivorous  and  omnivorous  animals  on  the  one  hand 
and  the  herbivora,  particularly  ruminants,  on  the  other. 

EXPERIMENTS  ON  CABNIVOBA. 

The  earlier  experiments  made  upon  carnivora  as  a  rule  failed  to 
show  that  amids  could  to  any  degree  serve  to  protect  the  protein  tis- 
sue of  the  body  from  katabolism.  More  recent  experiments  have 
upon  the  whole,  confirmed  these  results.  While  numerous  inves- 
tigations have  shown  beyond  a  doubt  that  the  body  has  the  power 
to  build  up  protein  from  the  mixture  of  at  least  very  simple  cleavage 
products  obtained  by  prolonged  enzym  hydrolysis,  or  even  by  acid 
hydrolysis/'  experiments  in  which  single  amino  acids  or  even  three  or 

1  Compare  Armsby,  Henry  P.    The  Principles  of  Animal  Nutrition.    Third  edition,  revised,  New  York, 
1908,  pp.  52-58. 

2  Asparagin  is  the  amid  of  aspartic  acid,  which  is  one  of  the  cleavage  products  of  all  proteins  thus  far 
investigated. 

8  Voltz,  W.  Untersuchungen  iiber  die  Vcrwertung  des  Detains  durch  den  Wiederkiluer  (Schaf).  Archiv 
fur  die  gesammte  Physiologic.  Band  110,  Heft,  5-0,  pp.  307-333.  Bonn,  1907. 

4  Zeitschrift  Zuckerindustrie  in  Bohmen,  Band  27,  p.  14. 

6  Abderhalden,  Emil,  and  Frank,  Oskar.  Weiterer  Beitrag  zur  Frage  nach  der  Verwertung  von  tief 
abgebautem  Eiweiss  im  tierischen  Organismus.  XII  Mitteilung.  Zeitschrift  fur  physiologische  Chemie. 
Band  64,  Heft  2-3,  pp.  158-163.  Strassburg,  1910. 


EXPERIMENTS   ON    CARNTVORA.  7 

four,  or  the  mixture  contained  in  vegetable  extracts,  have  been  fed 
have  failed  to  establish  satisfactorily  the  ability  of  the  organism  to 
form  protein  from  them.  The  principal  investigations  on  this  ques- 
tion have  been  by  Voltz,  Lehmann,  Rosenfeld,  and  Miiller. 

Voltz1  has  reported  three  series  of  experiments  upon  dogs.  In 
the  first  he  compared  the  effect  of  adding  to  the  basal  ration  consumed 
by  a  mature  dog,  on  the  one  hand,  1  gram  of  nitrogen  in  the  form  of 
protein  of  various  kinds  and  on  the  other  hand  one-half  gram  in  the 
form  of  protein  and  the  remainder  as  asparagin.  As  regards  the  rel- 
ative values  of  the  proteins,  the  experiments  are  open  to  the  criticism 
that  the  protein  content  of  the  basal  ration  was  too  high.  The  latter 
contained  0.37 -to  0.75  gram  total  nitrogen  per  kilogram  live  weight,  as 
compared  with  the  0.2  to  0.3  gram  per  kilogram  which  apparently 
suffices  for  maintenance.2  In  other  words,  surplus  protein  was  being 
katabolized  in  the  body  in  these  experiments.  It  is  not  surprising 
to  find,  therefore,  that  the  effects  upon  the  nitrogen  balance  of  adding 
more  protein  to  the  ration  were  irregular  and  difficult  to  interpret. 
The  asparagin,  however,  in  every  case  was  found  to  be  inferior  to 
protein  in  its  power  of  maintaining  or  increasing  the  body  protein. 
It  may  be  noted  also  in  passing  that  the  asparagin  increased  the  nitro- 
gen content  of  the  feces.  If  we  may  judge  from  the  results  upon 
herbivora,  to  be  considered  subsequently,  this  may  be  ascribed  to 
an  increase  in  the  so-called  metabolic  products,  especially  mucus 
and  epithelial  detritus. 

In  the  second  series  of  experiments,  also  on  a  mature  dog,  a  basal 
ration  containing  about  0.75  gram  nitrogen  per  kilogram  body  weight 
was  fed  in  the  first  and  last  periods.  In  the  remaining  periods  1 
gram  of  nitrogen  in  various  forms  (asparagin.  ammonium  acetate, 
acetamid,  and  glycocol)  was  added  to  the  basal  ration.  Yoltz  bases 
his  conclusions  upon  the  average  of  the  last  7  days  of  the  10-day 
periods.  His  results  show  during  the  periods  of  nonprotein  feeding 
an  excess  of  nitrogen  in  the  urine  over  the  average  of  the  basal  period 
greater  than  the  amount  of  nonprotein  nitrogen  added  to  the  ration. 
That  is,  the  nonproteins  diminished  the  gain  of  nitrogen  by  the  body. 
In  his  final  table  Voltz  assumes  the  fecal  nitrogen  for  each  period  as 
equal  to  that  of  the  first,  disregarding  an  observed  steady  increase 

'  Voltz,  W.  ('bor  don  Kintluss  versHiir< loner  Kiweisskorper  mid  einiger  Herivate  ders»>llx>n  auf  den 
StickstotTmnsatr.,niit  besonderer  Bwilckslchtigung  des  Asparagins.  Archivfiir  die  gesaininte  Physiologic. 
Band  107,  Heft  7-9,  ]>p.  3WM14.  Bonn.  1SH15. 

('her  den  Kinfluss  des  Lezithins  auf  den  Kiweissuinsatz  ohnc  gleiehzeiiige  Asparaginznfuhr  mid  l>el 
flegrn wart  dieses  Amids.  Zeitschrift  fiirdio  gesanunte  Physiologic,  Band  107,  Heft  7-9,  pp.  415-425.  Bonn, 
1905. 

tvber  das  Verhalten  einiger  Amidstibstanzen  allein  und  ini  Geinisch  iin  StolTwechsel  der  Kaniivoren, 
Zeitschrift  fur  die  gesaminte  Physiologic,  Band  112.  Heft  7-8,  pp.  413-4.TX.  Bonn,  1900. 

Voltz,  W.,and  Yakuwa,  (!.  tll>er  die  Verwertung  verschiedener  Ainidsubstanzen  (lurch  Carnivoren. 
Zeitchrift  fur  die  gesammte  I'hysiologie,  Band  121.  Heft  3-4,  pp.  117-149.  Bonn.  1908. 

'Compare  Armsby,  Principles  of  Animal  Nutrition,  p.  143,  1908;  and  Chitteudeu,  The  Nutrition  of 
Man,  Chapter  VII,  1907. 


8  NUTRITIVE   VALUE    OF    NONPROTEIN    OF    FEEDING    STUFFS. 

in  the  subsequent  periods,  including  the  last  basal  ration.  In  this 
manner  he  computes  that  in  period  6,  in  which  a  mixture  of  the  non- 
proteins  used  in  the  preceding  periods  was  fed,  the  nitrogen  katabolism 
remained  practically  the  same  as  in  the  basal  period,  and  hence 
concludes  that  the  mixture  was  more  effective  in  this  respect  than 
its  ingredients  separately,  and  argues  that  experiments  upon  a  single 
amid  or  amino  acid  are  inconclusive  as  regards  the  value  of  the 
mixed  nonproteins  of  natural  products.  The  general  correctness  of 
this  point  of  view  was  pointed  out  in  the  introduction,  but  Kellner  1 
has  called  attention  to  the  rather  remarkable  nature  of  Voltz' s  calcu- 
lations, and  has  shown  that  when  the  actual  analytical  results  are  made 
the  basis  of  the  calculation  it  appears  that  the  animal,  which  in  the 
first  period  was  gaining  nitrogen,  was  steadily  approaching  a  con- 
dition of  nitrogen  equilibrium  in  the  last  period,  and  that  the  addition 
of  the  nonproteins  to  the  ration  produced  no  distinct  effect. 

In  his  third  series  of  experiments,  upon  one  growing  and  two 
mature  dogs,  Voltz  followed  the  same  general  plan  as  in  the  previous 
series,  but  used  five-day  periods,  alternating  with  similar  periods  on 
the  basal  ration.  As  before,  1  gram  of  nitrogen  in  the  same  four 
forms  was  added  to  a  basal  ration  containing,  in  the  case  of  the  mature 
animals,  0.58  to  0.73  gram,  and  in  that  of  the  growing  animals  from 
0.43  to  0.46  gram  nitrogen  per  kilogram  body  weight;  that  is,  mate- 
rially more  than  the  minimum  protein  requirement.  In  these 
experiments,  contrary  to  the  earlier  ones,  the  amount  of  nitrogen 
contained  in  the  feces  was  slightly  less  instead  of  greater  in  the 
periods  in  which  the  nonproteins  were  fed.  The  results  are  cor- 
rected for  the  effect  of  the  nonproteins  upon  the  nitrogen  excretion 
at  the  beginning  of  the  following  basal  period  from  the  data  for  the 
daily  nitrogen  excretion.  Thus  corrected,  the  periods  in  which 
acetamid,  ammonium  acetate,  and  a  mixture  of  nonproteins  were 
consumed  showed  a  considerable  retention  of  nonprotein  nitrogen, 
while  the  periods  with  asparagin  and  with  glycocol  failed  to  do  so. 
It  may  be  noted  that  dog  No,  3  (mature)  showed  a  distinct  tendency 
toward  a  gain  of  nitrogen  even  on  the  basal  ration,  while  dog  No.  2 
(immature)  did  not. 

Rosenfeld,2  at  the  suggestion  of  C.  Lehmann,  investigated  the 
influence  of  the  bulk  of  food  upon  the  utilization  of  asparagin  by  the 
dog  by  cooking  very  finely  ground  hay  with  the  remaining  feed. 
He  found  in  the  hay  periods  a  considerable  retention  of  the  nitrogen 
of  the  asparagin  added  to  the  ration,  while  when  albumin  was  sub- 
stituted for  asparagin  the  retention  was  less.  He  concludes  that 

»  Kellner,  O.  Zur  Kenntniss  der  Wirkung  nicht  eiweissartiger  Stickstoffverbindungen  auf  den 
Stickstoflumsatz  im  Tierkorper.  Archiv  fur  die  gesammte  Physiologie,  Band  113,  Heft  7-8,  pp.  480-486. 
Bonn,  190C.  See  p.  484. 

*  Cited  by  Voltz,  Archiv  fiir  die  gesammte  Physiologie,  Band  107,  Heft  7-9,  p.  305. 


EXPERIMENTS  ON  CARNIVORA.  9 

under  these  conditions  there  is  either  an  action  of  the  ferment 
organisms  similar  to  that  occurring  in  herbivora  !  or  that  some 
substances  resorbed  from  the  hay  facilitate  the  utilization  of  the 
asparagin. 

Lehmann  2  reports  experiments  performed  by  Rosenfeld  on  another 
phase  of  the  same  general  idea,  viz,  that  the  rate  of  resorption  may 
materially  affect  the  nutritive  value  of  nonprotein.  He  points  out 
that  in  experiments  upon  carnivorous  animals  soluble  nonproteins 
(usually  asparagin)  have  commonly  been  given  in  a  single  dose  s •> 
that  they  were  rapidly  resorbed,  while  with  herbivorous  animals,  on 
the  contrary,  the  resorption  from  ordinary  feeding  stufTs  would  be 
relatively  slower.  In  the  first  case,  therefore,  the  system  would  be 
more  or  less  flooded  temporarily  with  the  nonprotein,  which  would 
presumably  be  subject  to  rapid  nitrogen  cleavage;  and  Lehmann 
cites  Graffenberger's  experiments 3  in  illustration  of  this  effect. 
To  test  the  truth  of  this  view,  Lehmann  prepared  a  mixture  of  aspara- 
gin and  a  solution  of  celluloid  and  allowed  it  to  dry  out  in  small 
grains.  This  coated  asparagin  was  compared  with  untreated  mate- 
rial and  with  blood  albumin,  it  being  shown  by  preliminary  trials 
that  the  solution  of  the  asparagin  was  rendered  less  rapid  by  the 
treatment,  but  that  it  was  completely  digested  by  the  animal.  The 
subject,  a  dog,  received  a  basal  ration,  consisting  of  meat,  rice,  lard, 
and  ash  ingredients,  which  contained  0.55  gram  nitrogen  per  kilo- 
gram of  live  weight.  No  statement  of  the  energy  content  of  the 
ration  is  made,  but  the  fact  that  the  nitrogen  katabolism  seems  to 
have  steadily  increased  in  the  basal  periods  suggests  an  insufficient 
supply.  Increasing  amounts  of  nitrogen  in  the  three  forms  men- 
tioned were  added  in  successive  three-day  periods  in  amounts  ranging 
from  1  to  2  grams,  a  period  upon  a  basal  ration  preceding  each  of  the 
three  series  of  trials. 

In  summarizing  his  results  Lehmann  compares  for  each  three-day 
period  the  excess  of  nitrogen  digested  over  that  digested  in  the  period 
immediately  preceding  with  the  excess  of  nitrogen  found  in  the  urine 
of  the  same  three  days.  Compared  in  this  way  he  finds  that  the  free 
asparagin  increased  slightly  the  loss  of  nitrogen  from  the  body, 
while  the  coated  asparagin  maintained  nitrogen  equilibrium  and  the 
blood  albumin  caused  a  slight  gain.  Xeglecting  the  minute  amounts 
of  nitrogen  given  off  in  the  hair,  the  results  may  also  be  summarized 
as  in  the  following  table: 


1  Compare  p.  13. 

'  Lehmann,  C.  Beitriige  zur  Kenntniss  cler  Wirkung  dps  Asparagins  aiif  don  Stickstoffumsatz  im 
ThierkSrper.  Archiv  fiir  die  gesammte  Physiologic,  Band  11.',  Heft  7-8.  pp.  330-3.51.  Bonn,  IDfXi. 

'  Graffenberger,  L.  Versucheztir  Feststellungdeszeitlirhen  Ahlaiifesdcr  Zereetzung  von  Fibrin,  I/eim. 
Pepton  und  Asparagin  im  mensohlichen  Organismus.  Zeitschrift  fiir  Biologic,  Band  28,  pp.  31S-344. 
Miinchen  and  Leipzig,  1891. 

95833°— Bull.  139-11— 


10          NUTRITIVE   VALUE    OF    NONPROTEIN    OF    FEEDING    STUFFS. 
Average  nitrogen  per  day — Lehmann's  experiments. 


Items. 

Digested. 

In  urine. 

Gain  or 
loss. 

Basal  period 

Grams. 
5  13 

Grams. 
4  99 

Grams. 
+0  14 

Asparagin,  coated  ... 

6.55 

6  53 

+0  02 

Basal  period  

5.11 

5  10 

+0  01 

Asparagin,  free 

6  66 

6  85 

0  19 

Basal  period 

5  11 

5  19 

0  08 

Blood  albumin  

6.43 

6  40 

+0  03 

Basal  period 

5  14 

5  28 

0  14 

It  appears  from  these  results  that  the  asparagin  had  a  tendency  to 
increase  the  breaking  down  of  nitrogenous  body  material,  but  the 
differences  hardly  seem  very  significant.  Kellner 1  has  criticized 
Lehmann's  conclusions  because  he  failed  to  take  due  account  of  the 
lag  in  the  excretion  of  urinary  nitrogen  and  of  the  gradual  increase 
in  the  nitrogen  katabolism  upon  the  basal  ration.  He  shows  from 
Lehmann's  data  that  some  of  the  nitrogen  added  to  the  basal  ration 
appeared  in  the  urine  on  the  first  day  or  two  of  the  following  basal 
period  (these  days  are  not  included  in  the  data  of  the  table).  Recal- 
culating the  results  from  this  point  of  view,  Kellner  computes  that 
both  forms  of  asparagin  had  an  equal  effect  in  materially  increasing 
the  nitrogen  katabolism.  while  the  albumin,  on  the  other  hand, 
diminished  it  somewhat.  In  reply  Lehmann  2  denies  that  Kellner  is 
justified  in  assuming  an  increasing  nitrogen  katabolism  for  the  basal 
periods  and  thus  estimating  what  the  nitrogen  balance  would  have 
been  in  each  period  without  the  added  nitrogen.  By  comparing  the 
actual  figures  Lehmann  shows  a  distinct  negative  balance  upon  the 
free  asparagin  as  compared  with  a  slight  positive  balance  on  the  coated 
asparagin  and  the  albumin. 

Miiller 3  has  repeated  Lehmann's  experiments  with  coated  and 
uncoated  asparagin,  with  the  difference  that  he  added  more  nitrogen 
to  the  basal  ration  in  proportion  to  the  live  weight  than  did  Lehmann 
and  also  added  sufficient  nonnitrogenous  material  to  compensate  for 
the  difference  in  energy  between"asparagin  and  an  amount  of  albumin 
containing  the  same  quantity  of  nitrogen.  On  the  basal  periods  the 
ration  contained  0.56  to  0.64  gram  nitrogen  per  kilogram  live  weight, 
and  the  animal  was  quite  exactly  in  nitrogen  equilibrium.  After 
correcting  the  observed  results  in  each  period  for  the  influence  of  the 
lag  of  nitrogen  excretion  as  shown  by  the  succeeding  basal  period  he 

1  Kellner,  O.    Zur  Kenntnis  der  Wirkung  nicht  eiweissartiger  Stickstoflverbindungen  auf  "den  Stick- 
stoSumsatz  im  Tierkorper.    Archiv  fur  die  gesammte  Physiologic,  Band  113,  Heft  7-8,  pp.  480-486.    See 
p.  484.    Bonn,  1906. 

2  Lehmann ,  C.    Nochmals  zur  Wirkung  des  Asparagins  auf  den  Stickstoflumsatz  im  Tierkorper.     Archiv 
fur  die  gesammte  Physiologie,  Band  115,  Heft,  115,  pp.  448-451.    Bonn,  1906. 

'Miiller,  Max.  Weitere  Untersuchungen  iiber  die  Wirkung  des  Asparagins  auf  den  Stickstoflumsatz 
und  Ansatz  des  Tierkorpers.  Archiv  fur  die  gesammte  Physiologie,  Band  117,  Heft  10-12,  pp.  497-537. 
Bonn,  1907. 


EXPERIMENTS    ON    CARNTVORA.  11 

finds  some  retention  of  the  added  nitrogen  in  all  cases,  but  notably 
less  in  the  case  of  the  free  asparagin.  Including  a  correction  for  the 
small  gain  or  loss  in  the  basal  ration,  he  computes  a  retention  of  the 
following  amounts  of  nitrogen  per  day: 

(!ram. 

Asparagin,  coated 0.  35 

Asparagin,  uncoated 18 

Blood  albumin 35 

Dextrin 06 

In  a  subsequent  investigation  '  Miiller  has  compared  the  effect  of 
blood  albumin  with  that  of  the  mixed  nitrogenous  material  contained 
in  an  aqueous  extract  of  hay.  A  mature  dog  received  a  basal  ration 
containing  0.55  gram  nitrogen  per  kilogram  live  weight.  To  this  were 
added  in  subsequent  periods  equal  amounts  of  nitrogen  in  the  forms  of 
blood  albumin  and  of  hay  extract,  no  addition  of  nonnitrogenous 
material  being  made  and  no  correction  being  made  for  the  lag  in  the 
nitrogen  excretion.  A  small  plus  balance  of  nitrogen  was  observed 
in  both  cases,  but  it  was  much  smaller  with  the  hay  extract  than  with 
the  blood  albumin,  being,  indeed,  almost  or  quite  negligible. 

Muller's  experiments  have  also  been  criticized  by  Kellner  2  on  the 
ground  that  in  the  second  series  the  nitrogen  lag  was  not  taken  account 
of,  while  he  suspects  analytical  errors  in  the  nitrogen  determinations 
of  both  series  (although  this  is  denied  by  Miiller  3),  while  Friedlander  4 
regards  the  differences  observed  by  Miiller  as  within  the  limits  of 
analytical  error  and  also  criticizes  his  short  periods. 

Quite  aside,  however,  from  the  points  raised  by  Kellner  and  others, 
there  is  one  feature  of  all  these  experiments  which  renders  their 
results  inconclusive,  viz,  the  fact  that,  as  already  pointed  out,  the 
nitrogenous  substances  to  be  tested  were  added  to  a  basal  ration 
which  already  contained  a  surplus  of  protein  over  the  maintenance 
requirement.  When  the  animal  was  in  nitrogen  equilibrium  with 
the  basal  ration,  therefore,  the  nitrogenous  cleavage  products  arising 
from  the  digestion  of  the  protein  were  doubtless  being  deamidized 
to  a  considerable  extent  and  their  nitrogen  excreted  as  urea.  Such 
being  the  case,  while  additional  protein  might  cause  more  or  less 
gain  of  nitrogen  for  a  time,  additional  nonprotein  might  easily  pro- 
duce indirectly  a  similar  effect,  without  implying  any  formation  of 
protein  from  it,  simply  by  taking  the  place  of  some  of  the  cleavage 

1  Miiller,  Max.     Untorsnchungen  iiber  die  Niihrwirkung  iin  Hen  cnthaltener  NU-hteiwoLw.    Journal  fiir 
Landwirthschaft,  Hand  .V5.  pp.  PJ3  HI.     Berlin.  1907. 

2  Kellner.  O.     Notiz  betrefTenddie  Niihrwirkung  des  Asparagins.     Arcliiv  fiirdie  gesammte  Physiologic. 
Band  118,  Heft  11-12,  pp.  f>41-<>42.     Bonn,  1907. 

Kellner,  O.  Untersuchungen  iiber  die  Niihrwirkung  der  im  Hen  enhaltenen  nu-hleiwoissartiiren  Stu-k- 
stoffverbindungen.  Journal  fiir  Landwirtschaft,  Band  56,  pp.  49-.52.  Berlin,  Htas. 

'Miiller.  Max.  Richtigstellung  der  von  O.  Kellner  gemachten  kritischen  Bomerkiingen  Journal  fiir 
Landwirtschaft.  Jahrgang  5(i,  pp.  193-194.  Berlin,  1908. 

4  Friedlander.  Konrad.  JCtir  Frage  des  Elwei.ssersatzes  dtirch  Amide.  Die  landwirtschaft lichen  Ver- 
snchs-Stationen,  Band  H7,  pp.  283-312.  Berlin,  1907.  See  pp.  289-292. 


12          NUTRITIVE   VALUE   OF    NONPROTEIN   OF   FEEDING   STUFFS. 

products  whose  nitrogen  was  previously  split  off.  In  other  words,  it 
is  possible  that  the  nitrogen  stored  up  in  the  body  had  its  origin  in 
the  surplus  protein  of  the  food  and  not  in  the  nonprotein  added. 
The  fact  that  the  retention  of  nitrogen  when  nonprotein  was  fed  was 
frequently  less  than  that  when  a  corresponding  amount  of  protein 
was  given  may  possibly  be  explained  by  the  fact  that  one  or  two 
single  ammo  acids  could  not  fully  replace  in  this  respect  the  mixture 
arising  from  the  digestion  of  the  protein  of  the  food.  Taking  all 
these  points  into  consideration,  we  seem  warranted  in  concluding 
that  it  has  not  yet  been  satisfactorily  shown  that  carnivorous  animals 
can  produce  body  protein  either  from  one  or  a  few  of  the  amino 
acids  or  from  the  mixture  of  nonproteins  contained  in  the  vegetable 
products  thus  far  investigated. 

EXPERIMENTS  ON  OMNIVORA. 

To  a  number  of  earlier  investigations  on  omnivorous  animals, 
mostly  rats  and  mice,  may  be  added  more  recent  experiments  by 
Henriques  and  Hansen  l  upon  rats,  directed,  like  the  earlier  ones,  to 
a  somewhat  different  aspect  of  the  problem  than  that  studied  in  the 
foregoing  experiments  on  carnivora.  They  investigated  the  ques- 
tion whether  asparagin  or  the  mixture  of  nonprotein  nitrogenous 
materials  found  in  various  vegetable  substances  (potatoes,  roots, 
and  seedlings  of  beans  and  barley),  when  constituting  the  sole  source 
of  protein,  were  capable  of  maintaining  the  protein  tissue  of  the  body. 
Their  results  fully  confirmed  the  earlier  ones  of  Politis  and  of 
Gabriel  and  showed  that  under  these  circumstances  the  nonprotein 
can  not  perform  the  functions  of  protein.  A  continuous  loss  of  nitro- 
gen from  the  body  was  observed,  which  was  substantially  at  the  same 
rate  as  when  only  nonnitrogenous  nutrients  were  consumed. 

EXPERIMENTS  ON  HERBIVORA. 

But  while  there  is  no  satisfactory  evidence  that  either  single  non- 
proteins  or  the  mixtures  of  them  found  in  vegetable  products  are 
available  to  either  carnivora  or  omnivora  as  a  source  of  protein,  with 
herbivora,  as  previously  indicated,  the  case  is  different.2  With  the 
latter  class  of  animals  a  considerable  number  of  experiments  are  on 
record,  of  which  Weiske's  are  the  earliest,  which  have  shown  that 
asparagin  added  to  a  ration  poor  in  protein  is  able  partially  to  replace 
the  latter.  Zuntz  appears  to  have  been  the  first  to  advance  the  idea 
that  this  marked  difference  between  the  two  classes  of  animals  might 
be  due  to  the  difference  in  their  digestive  processes  and  particularly 

1  Henriques,  V.,and  Hansen,  C.    Uber  die  Bedeutung  der  sogenannten  Pflanzenamide  fur  den  Stick- 
stoflumsatz  im  tierischcn  Organismus.    Zeitschrift  fur  physiologische  Chcmie,  Band  54,  pp.  109-187- 
Strassburg,  1907-8. 

2  Compare  Armsby,  Principles  of  Animal  Nutrition,  pp.  53-58.    New  York,  1908. 


EXPERIMENTS   ON    HERBIVORA.  13 

to  the  great  development  of  organized  ferments  in  the  digestive  tract 
of  herbivora.  He  suggests  that  soluble  nonprotein  introduced  into 
the  digestive  canal  of  herbivora  may  be  used  as  nitrogenous  food  by 
the  organisms  in  preference  to  the  less  soluble  proteins,  particularly 
in  the  first  stomach  of  ruminants,  before  the  digestion  of  the  pro- 
teins begins,  so  that  the  latter  are  to  a  greater  or  less  extent  protected 
from  destruction,  while  it  is  possible  that  the  nonproteins  are  thus 
synthesized  to  protein  by  the  organisms  and  later  digested  by  the 
animal 

The  validity  of  this  suggestion  was  confirmed  by  Kellner  !  in 
experiments  upon  lambs,  in  which  the  gain  of  nitrogen  by  the  animal 
upon  a  ration  poor  in  protein  was  very  notably  increased  by  the  addi- 
tion to  the  ration  not  only  of  asparagin,  but  also  of  ammonium 
acetate,  which  it  has  not  been  supposed  that  the  body  tissues  can 
synthesize  to  protein.  lie  showed  also  that  this  effect  was  accom- 
panied by  an  increased  digestibility  of  the  crude  fiber  and  nitrogen- 
free  extract  of  the  ration,  presumably  due  to  the  greater  activity  of 
the  micro-organisms  under  the  influence  of  the  soluble  nitrogenous 
food.  Tryniszewsky  also  observed  a  similar  effect  upon  the  digesti- 
bility of  the  nonnitrogenous  ingredients  of  the  feed,  although  the 
effect  upon  the  nitrogen  balance  was  less  decided. 

This  view,  which  has  been  generally  accepted,  regards  the  value  of 
the  nonprotein  in  the  feed  of  herbivora  as  indirect,  due  to  its  pro- 
tecting protein  from  destruction.  The  multiplication  of  organisms 
under  the  influence  of  an  increased  supply  of  nonprotein  nitrogen  has, 
however,  another  aspect,  as  appears  when  we  inquire  what  becomes 
of  the  nitrogen  which  they  assimilate.  Presumably  it  becomes  part 
of  the  protoplasm  of  the  organisms  and  in  this  way  may  produce  one 
of  two  effects.  If  any  of  the  nitrogen  of  the  feces  has  its  origin  in 
the  nonprotein  of  the  feed — that  is,  if  the  bacterial  protein  formed 
from  the  latter  is  indigestible — it  is  necessary  to  modify  considerably 
the  ordinary  interpretation  of  digestion  experiments  upon  rations 
containing  nonproteins.  Hitherto  the  latter,  being  soluble  in  water, 
have  been  regarded  as  totally  digestible.  If,  however,  part  of  the 
fecal  nitrogen  is  derived  from  them,  the  digestion  experiment  as 
ordinarily  computed  gives  too  high  a  result  for  the  resorbed  nonpro- 
tein and  correspondingly  too  low  a  result  for  the  resorbed  protein, 
and  this  leads  to  ascribing  to  the  former  nutritive  effects  really  due 
to  the  latter. 

On  the  other  hand,  if  the  bacterial  protein  formed  from  the  non- 
proteins  is  digestible,  we  have  in  the  activity  of  these  organisms  in 

i  Kellnor,  O.     rntorsiichuiigon  U)NT  den  Kiutluss  des  Asparanins  und  Anunoniaks  auf  don  Kiweissmn- 
satz  der  Wiederkauer.    Zeitschrift  fiir  Biologic,  Band  39,  pp.  313-370.    Miinchen  und  Ix'ipzi*,',  1900. 


14 


NUTRITIVE   VALUE   OF    NONPROTEIN   OF   FEEDING   STUFFS. 


the  digestive  tract  a  means  of  converting  nonprotein  into  available 
protein,  and  so  virtually  adding  to  the  protein  supply  in  the  food  by 
a  sort  of  symbiosis.  It  may  be  remarked  that  the  presence  of  bac- 
teria in  the  feces  does  not  necessarily  disprove  this,  since  the  latter 
may  readily  come  from  the  lower  part  of  the  alimentary  canal. 

Since  the  interpretation  of  the  results  of  feeding  experiments  upon 
herbivora  must  be  materially  affected  by  the  question  of  the  fate  of 
the  nonprotein  in  the  digestive  tract,  it  seems  necessary  to  consider 
this  aspect  of  the  question  first. 

BEHAVIOR     OF     NONPROTEINS     IN     DIGESTIVE     TRACT     OF     HERBIVORA. 

There  are  a  considerable  number  of  experiments  on  record  in  which 
the  protein  of  the  feces  has  been  distinctly  increased  by  feeding 
materials  containing  much  nonprotein  nitrogen,  and  this  has  been 
interpreted  as  indicating  the  formation  by  bacteria  in  the  digestive 
tract  of  indigestible  nitrogenous  compounds.  In  other  cases,  how- 
ever, scarcely  any  such  effect  has  been  observed. 

In  the  early  experiments  of  Weiske,  as  well  as  in  the  later  ones  of 
Chomsky,  more  or  less  increase  in  the  total  nitrogen  of  the  feces  was 
observed  to  result  when  asparagin  was  fed.  In  Kellner's  experi- 
ments upon  lambs,  just  referred  to,  asparagin  was  substituted  for 
an  equal  weight  of  starch  in  the  first,  third,  and  fourth  series,  while 
in  the  second  and  third  periods  of  the  second  series  ammonium  ace- 
tate and  asparagin,  respectively,  were  added  to  the  basal  ration. 
The  total  excretion  of  fecal  nitrogen  was  as  follows : 

Excretion  of  fecal  nitrogen — Kellner's  experiments. 


Items. 

Lamb  I. 

Lamb  II. 

Series  I: 
Period  1  basal  ration                                                                 

Grams. 
6.51 

Grams. 
6.32 

Period  2,  asparagin  substituted            .              

5.54 

5.77 

Series  II: 
Period  1  ,  basal  ration                            .                             

6.09 

6.17 

Period  2,  ammonium  acetate  added  

6.63 

6.16 

6.25 

5.63 

Series  III: 

7.17 

6.95 

Period  2  asparagin  substituted            .                             .  .        

7.08 

6.85 

Series  IV: 

7.66 

6.09 

Period  2  asparagin  substituted          .  .                                   

7.70 

6.28 

Period  3,  basal  ration  

7.14 

5.87 

Average: 
Basal  ration                  

6.79 

6.51 

6.64 

6.13 

Ammonium  acetate                                                                        

6.63 

6.16 

The  experiments  of  Tryniszewsky  also  showed  substantially  the 
same  result,  the  crude  protein  of  the  feces  being  in  period  2,  basal 
ration,  206  grams;  period  3,  asparagin,  210  grams;  period  4,  basal 
ration,  191  grams. 


BEHAVIOR   IN   DIGESTIVE   TRACT   OF    HERBIVORA. 


15 


Neither  of  the  foregoing  experiments  shows  very  distinct  evidence 
of  any  increase  of  the  nitrogenous  matter  of  the  feces  as  a  result  of 
feeding  asparagin  or  ammonium  acetate.  It  must  be  remembered, 
however,  that  the  feces  contain  nonprotein  nitrogen  in  the  form  of 
metabolic  products.  It  is  possible,  therefore,  that  the  protein  nitro- 
gen might  have  increased  in  these  experiments  even  though  the  total 
nitrogen  did  not.  In  more  recent  experiments,  therefore,  the  com- 
parison has  been  made  upon  the  protein  nitrogen  of  the  feces — that 
is,  the  nitrogen  which  is  either  insoluble  in  water  or  precipitable  by 
copper  hydrate.  Experiments  by  Andrlik,  Velich,  and  Stanek,1  in 
which  glutaminic  and  aspartic  acids  were  added  to  the  basal  ration 
of  a  young  wether,  yielded  the  following  results,  which  fail  to  show 
any  material  influence  of  the  added  nonprotein  upon  the  fecal  nitro- 
gen. An  earlier  series  2  likewise  showed  no  increase  in  the  total 
nitrogen  of  the  feces  as  a  result  of  adding  betain  to  the  basal  ration. 

Kesults  of  Andrlik,   Velich,  and  Stanch' s  experiments. 


Items. 

Feed. 

Feces. 

Protein 
nitrogen. 

Non- 
protein 
nitrogen. 

Protein 
nitrogen. 

Non- 
protein 
nitrogen. 

I.  Basal  ration 

Grams. 
8.42 
8.52 
8.63 
8.  IB 
8  58 

Grams. 
1.190 
3.  072 
1.190 
3.  296 
1.190 

Grains. 
4.  067 
4.  443 
4.350 
3.990 
4.  425 

Grama. 
390 
450 
350 
410 
350 

II.  Glutaminic  acid 

III.  Basal  ration                                               .        

IV.  Aspartic  acid.                                             

Average  on  basal  ration                                                     .   . 

8.39 
8.58 

1.190 
3.  1S4 

4.  2S1 
4.210 

303 

430 

Average  on  nonprotx'in  ration                              

The  experiments  upon  which  special  stress  has  been  laid,  however, 
are  those  of  Voltz  3  and  of  Friedlander.4 

Voltz  fed  to  a  sheep  a  ration  consisting  of  straw,  potatoes,  and 
molasses,  or  the  distiller's  residues  from  the  latter — that  is,  a  ration 
poor  in  protein  and  rich  in  nonprotein.  The  results,  so  far  as  they 
bear  upon  the  particular  point  under  discussion,  are  shown  in  the 
following  table,  from  which  it  appears  that  without  exception  more 
protein  was  found  in  the  feces  than  in  the  feed. 

'Andrlik,  K.,  and  Velich,  K.  Ueber  die  IxMleutung  der  Glutamin  und  Asparaginsiiure  als  Nahrstoffe 
JL«itschrift  f iir  Zuckerindustrie  in  Bohmen,  Jahrgang  32,  Heft  ii,  pp.  313-342.  Prag,  190s. 

1  Velich,  Alois,  and  Stanek,  Vladimir.  Ueberdas  Betain  in  physiologischchemischer  Bfziehiing.  Zweit;T 
Bericht.  Zeitschrift  fur  Zuckerindustrio  in  Bohmen,  Jahrgang  29,  Heft  4.  pp.  205-219.  I'rag.  l!X)5. 

'Voltz,  \V.  Ueber  die  Verwertung  des  Amidgemisches  der  Melasse  durch  den  Widerkauor.  Archiv 
fiirgesammte  Physiologic,  Band  117,  Heft  10-12,  pp.  541-503.  Bonn,  1907. 

4  Friedlander,  Konrad.  Zur  Frage  des  Eiweissersatzes  durch  Amide.  Die  Landwirtschaftliehen 
Versuchs-Stationen,  Band  67,  pp.  283-312.  Berlin,  1907. 


16          NUTRITIVE  VALUE   OF    NONPROTEIN    OF    FEEDING  STUFFS. 
Protein  nitrogen  in  feed  andfeces — Voltz's  experiments. 


Periods. 

Daily  feed. 

Protein  nitrogen 
per  day. 

Straw. 

Potatoes. 

Molasses. 

Distil- 
ler's resi- 
due from 
molasses. 

In  feed. 

In  feces. 

I  . 

Grams. 
500.0 
498.4 
497.9 
498.4 
394.0 

Grams. 
500 
500 
500 

Grams. 

Grams. 
200 

Grams. 
3.42 
3  42 

Grams. 
4.41 
3.92 
3.43 
3.61 
2.98 

II 

400 
400 
600 
500 

III 

3.42 
2.96 
2.42 

IV   

V  

In  Friedlander's  experiments  also  two  sheep  received  rations  poor 
in  protein  but  containing  considerable  nonprotein  in  the  form  of  beet 
molasses.  In  two  periods  asparagin  was  added  to  this  ration  and  in 
one  a  form  of  commercial  protein.  The  results  are  shown  in  the  fol- 
lowing table,  from  which  it  appears  that  in  this  case,  too,  the  protein 
nitrogen  of  the  feces  was  in  excess  of  that  in  the  feed,  except  in  the 
period  in  which  commercial  protein  was  fed. 

Protein  nitrogen  in  feed  andfeces — Friedlander's  experiments. 


Periods. 

Rations. 

Protein  nitrogen. 

Hay. 

Molasses- 
peat. 

Aspara- 
gin. 

Protein. 

Sheep  I. 

Sheep  II. 

In  feed. 

In  feces. 

In  feed. 

In  feces. 

I... 

Grams. 
200 
200 
200 
200 
200 

Grams. 
C.25 
730 
730 
625 
625 

Grams. 

Grams. 

Grams. 
3.32 
3.45 
3.16 
10.  56 
3.32 

Grams. 
4.01 
5.56 
4.84 
4.35 
4.44 

Grams. 
3.32 
3.43 

Grams. 
4.09 
5.34 

II 

III 

30 

IV.. 

52 

10.56 
3.32 

4.21 
4.18 

V 

30 

Both  these  experiments  have  been  interpreted  as  showing  a  forma- 
tion of  indigestible  protein  from  the  nonprotein  of  the  feed. 

Just l  experimented  upon  tw»  growing  lambs  through  10  periods. 
In  the  first  and  last  periods  a  basal  ration  consisting  of  hay,  starch, 
and  sugar  was  fed.  In  the  intermediate  periods  nitrogenous  matter 
was  added  in  various  forms,  while  an  attempt  was  made  to  keep  the 
so-called  starch  values  of  the  rations  unchanged  by  diminishing  the 
starch  and  sugar,  although  this  object  was  not  entirely  attained.  In 
the  following  table  is  shown  for  each  period  the  difference  as  regards 
•nonprotein  nitrogen  and  protein  nitrogen  between  the  feed  and  the 
feces  of  the  period  and  the  average  of  the  two  basal  rations. 

1  Just,  Jaroslav.  Vergleichende  Untersuchungen  iiher  die  Wirkungen  des  Eiweisses  und  einiger  nich- 
teiweissartiger  Stickstoffverbindungenaiifden  Fleischansatzbeim  AYiederkauer.  Die  landwirtschaftlichen 
Versuch-Stationen,  Band  69,  pp.  393-460.  Berlin,  1908. 


BEHAVIOR   IN   DIGESTIVE   TRACT  OF   HERBIVORA.  17 

Protein  and  nonprotein  nitrogen  in  feed  andfeces — Jtist's  experiments. 


Feed. 

Feces—  Lamb  I. 

Feces—  Lamb  II. 

N  on  pro- 
tein ni- 
trogen. 

Protein 
nitrogen. 

Nonpro- 
tein  ni- 
trogen. 

Protein 
nitrogen. 

Nonpro- 
tein  ni- 
trogen. 

Protein 
nitrogen. 

Period  2  (molasses)  

Grams. 
2.02 
1.36 

Grams. 
10.01 
7.95 

Grams. 
0.95 
.76 

Grams. 
7.00 
5.94 

Grams. 
1.22 
0.75 

Gramt. 
7.12 
5.88 

I  '.;i^l  1  

Period  3  (gluten)               

1.26 

2.06 

.19 

1.06 

.47 

1.24 

'  1.52 
1.36 

>  11.17 

7.95 

1.03 
.70 

<;.oo 

5.94 

.90 
.  75 

(5.21 
5.88 

Basal                          

.16 

3.  22 

.27 

.00 

.15 

.33 

3.53 
1.30 

9.10 
7.95 

1.42 
.70 

7.07 
5.94 

1.48 
.75 

0.  70 
5.88 

Basal  

Period  5  (gluten)  

2.17 

1.15 

.66 

1.13 

.73 

.88 

1.48 
1.3fi 

10.51 
7.95 

.89 

.70 

5.96 
5.94 

.83 

.75 

5.99 
5.88 

Basal  

Period  0  (potato  "flocken'1). 

.12 

2.50 

.13 

.02 

.08 

.11 

3.24 
1.36 

10.  07 
7.  95 

1.16 

.70 

0.11 
5.94 

.97 
.75 

6.42 
5.88 

liasal  .  .                          

1.88 

2.72 

.40 

.17 

.22 

.54 

1  53 

11.82 
7.95 

.82 
.70 

0.  30 
5.94 

.(9 
.75 

0.  13 
5.88 

Basal  

1.30 

I'criod  8  (grass  extract) 

.17 

3.87 

.00 

.42 

—  .00 

.25 

3  35 

8.14 
7.95 

.43 

.70 

0.33 
5.94 

.43 

.75 

6.35 
5.88 

Basal 

1.30 

Period  9  (gluten) 

1.99 

.19 

-.33 

.39 

-.32 

.47 

1.51 
1.36 

11.10 
7.95 

.58 
.70 

0.08 
5.94 

.51 
.75 

6.32 
5.88 

Basal  ... 

.15 

3.15 

-.18 

.14 

-.24 

.44 

1  For  Lamb  IIT,  1.49  and  10.77,  respectively. 


Summarizing  these  differences,  we  find  that  the  average  increase  of 
protein  nitrogen  of  the  feces  over  that  present  in  the  basal  periods  was 
as  shown  in  the  following  table: 

Increases  in  protein  nitrogen  of  frees—  Just's  experiments. 


Items. 


Lamb  I.    Laml>  II. 


Average  of  gluten  

Grams.       Grains. 
0.10              0.2S 
1.06              1.24 
1.13                .88 

.17                .54 
.39                .47 

Molasses  

Malt  sprouts  extract  

Potato  "  flocken  "  

Grass  extract 

While  Just's  results  afford  no  instance  in  which  the  protein  nitrogen 
of  the  feces  exceeds  that  of  the  feed,  they  show  a  marked  effect  of  the 
extracts  and  especially  of  the  molasses  in  increasing  the  former. 
95833°— Bull.  139—11 3 


18 


NUTRITIVE  VALUE   OF    NONPROTEIN   OF   FEEDING  STUFFS. 


Kellner  and  his  associates  1  have  recently  reported  the  results  of 
two  series  of  experiments  upon  growing  lambs,  using  a  ration  com- 
posed of  oat  straw,  starch,  and  sugar;  that  is,  one  containing  very 
little  protein  and  practically  no  nonprotein.  To  this  mixture  there 
was  added  in  the  first  period  ammonium  acetate  and  asparagin  and 
in  the  second  period  wheat  gluten  containing  a  slightly  smaller  amount 
of  nitrogen,  the  energy  value  of  the  ration  being  kept  the  same  by  a 
reduction  in  the  amount  of  starch.  In  the  second  series  of  experi- 
ments, a  third  period  was  also  added  in  which  ammonium  acetate  and 
asparagin  were  added  to  the  ration  of  the  second  period.  The 
results,  so  far  as  they  relate  to  the  question  under  discussion,  are  as 
shown  in  the  following  table. 

Although  in  period  1  of  each  series  the  protein  nitrogen  of  the  feces 
is  greater  than  that  of  the  feed,  a  comparison  with  period  2  shows  that 
this  is  not  due  to  any  materially  greater  excretion  of  protein  nitrogen 
when  the  ammonium  acetate  was  fed — the  amounts  being  sensibly 
the  same — but  to  the  very  small  amount  of  true  protein  contained 
in  the  ration. 

Protein  and  nonprotein  nitrogen  in  feed  and  feces— Kellner' s  experiments. 


Items. 

In  feed. 

In  feces. 

Nonprotein 
nitrogen. 

Protein 
nitroeen. 

Nonprotein 
nitrogen. 

Protein 
nitrogen. 

Series  I: 
Lamb  I. 

Series  II: 
Lamb  II 

Lamb  II 

Period  1 

Orams. 
11.01 
.92 

14.27 
1.12 

14.89 
14.27 
1.12 
14.89 

Grams. 
1.18 
10.19 

1.55 
11.74 
11.62 
1.55 
11.72 
11.62 

Orams. 
2.53 

.07 

.71 
1.44 
1.03 
,             1.76 
1.86 
1.24 

Grams. 
4.20 
4.25 

4.37 
4.50 
4.48 
4.92 
4.33 
4.73 

Period  2.                   .                 

Period  1  .  .                           

Period  2 

Period  3 

I.  Period  1 

Periol  2 

Period  3 

The  foregoing  results  make  it  clear  that  there  is  a  marked  differ- 
ence between  different  forms  of  nonprotein  as  regards  their  effect 
upon  the  excretion  of  protein  nitrogen  in  the  feces.  While  Kellner's 
results  (both  the  earlier  and  later  ones)  and  those  of  Tryniszewski 
show  no  increase  as  the  result  of  the  addition  or  substitution  of 
ammonium  salts  or  asparagin,  those  of  Voltz,  Friedlander,  and  Just 
show  a  marked  increase  from  the  use  of  plant  extracts,  especially 
molasses.  Moreover,  Just's  results  show  striking  differences  between 
the  various  materials  which  are  by  no  means  related  to  the  content  of 
nonprotein,  as  is  evident  from  the  following  table,  which  shows  the 
increase  in  the  nonprotein  nitrogen  of  the  basal  ration  caused  by  the 

i  Kellner,  O.,  Eisenkolbe,  P.,  Flebbe,  R.,  and  Neumann,  R.  Untersuchungen  iiberden  Einfluss  einiger 
nicht-eiweissartiger  Stickstoffverbindungen  auf  den  Eiweissumsatz  beim  Wiederkauer.  Die  landwirts- 
chaftlichen  Versuch-Stationen,  Band  72,  pp.  437-458.  Berlin.  1910. 


BEHAVIOR   IN   DIGESTIVE   TRACT   OF    HERBIVORA. 


19 


addition  of  the  materials  named,  and  the  average  increase  of  the 
protein  nitrogen  in  the  feces. 

Comparative  increase  ofnonprotein  nitrogen  in  feed  andfeees — Just's  experiments. 


Items. 

Nonprotein 
nitrogen 
added  to 
basal  ration. 

Increase  of 
protein 
nitrogen 
in  feces. 

Gluten 

Grams. 
0.17 

Grams. 
0  22 

Molasses  

1.26 

1.15 

Malt  sprouts  extract 

2.17 

1  00 

Potato  "  floe  ken" 

1  88 

.36 

Grass  extract  .... 

1.99 

.43 

• 

These  general  results  are  abundantly  confirmed  by  those  obtained  by 
Morgenand  his  associates  in  the  course  of  their  extensive  investigations 
upon  the  nutritive  value  of  nonproteins  for  milk  production.  The  re- 
sults of  these  experiments  will  be  stated  in  greater  detail  immediately 
in  discussing  another  phase  of  the  subject.  In  a  considerable  number 
of  these  experiments  they  consistently  observed  no  increase  in  the 
protein  nitrogen  of  the  feces  to  result  from  the  substitution  or  addi- 
tion of  ammonium  salts  or  asparagin,  while,  on  the  other  hand,  plant 
extracts  had  a  marked  but  variable  effect  in  this  direction. 

These  well-established  facts  are  scarcely  consistent  with  the 
hypothesis  of  the  formation  of  indigestible  bacterial  protein  from  the 
nonprotein  of  the  feed.  If  such  a  formation  takes  place,  it  is  difficult 
to  see  why  it  should  not  be  quite  as  marked  in  the  case  of  readily 
soluble  and  assimilable  nitrogenous  substances  like  ammonium  salts 
as  in  that  of  plant  extracts,  nor  why  the  effect  in  the  latter  case 
should  not  be  more  or  less  proportional  to  the  amount  of  nonprotein 
present. 

Moreover,  Morgen J  has  shown  that  plant  extracts  containing 
relatively  little  nonprotein  nitrogen  may  also  cause  an  increase  of  the 
protein  nitrogen  of  the  feces.  He  compared  extracts  prepared  from 
grass  and  from  dried  sugar-beet  pulp,  containing  in  the  dry  matter — 


Dried  heet- 
pnlp  ex- 
tract. 

Grass  ex- 
tract. 

Protein 

Per  cent. 

2.84 

Per  cent. 
9.45 

Nonprotein  .  .  . 

.97 

4.20 

3.81 


13.65 


1  Morgen,  A.,  Beger,  C.,  and  Westhausser,  F.  Untersuchungen  iiber  die  Verwertung  der  Ammonsalze 
iind  der  nicht-eiweissartigen  StickUotTverbinduugen  dp.r  Futtennittel  fiir  die  Lel>enserhaltung  und 
Milchbildung,  sowie  iiber  die  Frage,  ob  aus  diesen  Stoflen  unverdauliches  Ehveiss  gebildet  wird.  Die 
landwirtschaftlichen  Versuch-Stationen,  Band  73,  pp.  285-3%.  Berlin,  1910.  See  pp.  320  and  350. 


20 


NUTRITIVE  VALUE   OF    NONPKOTEIN    OF   FEEDING  STUFFS. 


In  experiments  in  which  these  extracts  were  added  to  a  basal 
ration,  equivalent  amounts  of  starch  and  sugar  were  withdrawn,  and 
likewise  an  amount  of  protein  equal  to  the  true  protein  of  the  extracts, 
disregarding  the  nonprotein.  Upon  the  average  of  two  animals,  the 
protein  and  the  nonprotein  nitrogen  of  the  feed  and  the  protein  nitro- 
gen of  the  feces  were  as  shown  in  the  following  table.  While  the 
extract  of  dried  sugar-beet  pulp  increased  the  nonprotein  of  the  feed 
somewhat,  the  increase  of  protein  nitrogen  in  the  feces  is  relatively 
much  greater  than  that  caused  by  a  much  larger  increase  of  nonpro- 
tein in  the  grass-extract  ration. 

Comparison  of  extracts  of  dried  bat  pulp  and  of  grass — Morgeris  experiments. 


Items. 

In  feed.              \    In  feces. 

Protein 
nitrogen. 

Nonprotein 
nitrogen. 

Protein 
nitrogen. 

Basal  ration  

Grams. 
18.32 
18.  61 
19.35 

Grams. 
0.68 
1.03 
2.33 

Grams. 
5.39 
(i.ll 
7.43 

Extract  of  dried  beet  pulp 

Grass  extract  

Still  further,  Morgen  1  found  that  in  numerous  digestion  experi- 
ments upon  straw — that  is,  a  feed  containing  practically  no  non- 
protein — the  nitrogen  of  the  feces  exceeded  that  of  the  feed  in  15 
cases  out  of  18.  This  was  by  no  means  a  new  observation,  there 
being,  as  Morgen  points  out,  numerous  experiments  on  record  show- 
ing an  apparent  negative  digestibility  of  the  nitrogen  in  straw  and 
similar  feeding  stuffs  poor  in  protein. 

The  obvious  explanation  of  this  phenomenon  in  the  case  of  the 
straw  is  the  presence  of  the  so-called  nitrogenous  metabolic  products 
in  the  feces.  Their  presence  and  their  influence  upon  the  apparent  di- 
gestibility of  the  food  were  early  recognized,  but  the  first  attempt  at 
a  quantitative  determination  of  their  amount  in  the  excreta  of  herbiv- 
orous animals  is  due  to  Kellner,2  who  estimated  the  average  amount 
of  metabolic  nitrogen  in  the  feces  at""0.4  gram  per  100  grams  organic 
matter  digested.  Subsequent  investigations  by  Pfeiffer 3  and  by 
G.  Kiihn  4  have  resulted  in  the  development  of  a  method  by  which 

'  Loc.  cit.,  Band  73,  p.  337. 

2  Kellner,  O.    Beitrage  zur  quantitativen  Bestimmung  des  verdauten  Proteins.    Biedermann's  Cen- 
tralblatt  fur  Agrikulturchemie,  Jahrgang  9,  pp.  107-110.    Leipzig,  1880.    Untersuchungen  iiber  Protein 
verdanung.    Biedermann's  Centralblatt  fur  Agrikulturchemie,  Jahrgang  9,  pp.  703-7G5.    Leipzig,  1880. 

3  Pfeiffer,  Th.    Beitrage  zur  Frage  iiber  die  Bestimmung  der  Stoflwechselproducte  im  tierischen  Koth. 
Journal  fur  Landwirtschaft,  Jahrgang  33,  pp.  149-192.    Berlin,  1885. 

Pfeiffer,  Th.  Die  Verdaulichkeit  getrockneter  Riibenschnitzel.  sowie  die  Bestimmung  der  Verdauungs- 
coefficienten  stickstoffhaltiger  Futterbestandtheile  im  allgemeinen.  Journal  fur  Landwirtschaft,  Jahr- 
gang 34,  pp.  425-453.  Berlin,  1886. 

Pfeiffer,  Th.  Die  Bestimmung  des  Stickstoffs  der  Stoff wechselproducte.  Zeitschrift  fur  physiologische 
Chemie,  Band  10,  pp.  561-576.  Strassburg,  1886. 

«Kuhn,  Gustav,  Thomas,  A.,  Bottcher,  O.,  Kohler,  A.,  Zielstorff,  W.,  and  Barnstein,  A.  Untersuch- 
ungen iiber  die  Verdauung  stickstoffhaltiger  Futterbestandteile  durch  Behandlung  mit  Magen-  und  Pan- 
kreas-Extrakten.  Die  landwirtschaftlichen  Versuchs-Stationen,  Band,  44.  pp.  188-256.  Berlin,  1894 


BEHAVIOR   IN   DIGESTIVE   TRACT   OF    HERBIVORA.  21 

the  amount  of  metabolic  nitrogen  contained  in  the  feces  can  be  at  least 
approximately  determined.  The  method  is  based  upon  the  process 
of  artificial  digestion  with  pepsin  or  pepsin  and  trypsin  as  early  pro- 
posed by  Stockhardt  and  by  Hofmeister  and  worked  out  later  by 
Stutzer  l  for  the  laboratory  determination  of  the  digestibility  of  feeds. 
A  comparison  of  Stutzer's  method  with  natural  digestion  early  showed 
a  lower  result  in  the  latter  case,  especially  on  coarse  fodders  and  those 
poor  in  nitrogen;  and  since  it  is  difficult  to  see  how  the  action  of  the 
digestive  juices  could  be  less  effective  than  that  of  the  same  enzyms 
in  the  laboratory,  this  led  to  the  conclusion  that  the  difference  was 
due  to  metabolic  nitrogen.  To  test  this,  Pfeiffer  fed  2  pigs  a  nitrogen- 
free  ration  of  starch,  sugar,  oil,  paper  pulp,  and  ash  ingredients,  to 
which  in  a  subsequent  period  pure  digestible  protein  (conglutin)  was 
added.  From  the  first  experiment  the  feces  contained  an  average 
of  0.4  gram  nitrogen  per  100  grams  of  digested  dry  matter,  which  must 
have  been  in  the  form  of  metabolic  products,  since  the  feed  contained 
no  nitrogen.  In  the  second,  in  which  the  protein  was  assumed  to  be 
entirely  digestible,  practically  the  same  result  (0.39  gram  metabolic 
nitrogen)  was  obtained,  showing  that  the  result  of  the  first  experiment 
was  not  rendered  abnormal  by  the  lack  of  nitrogen  in  the  feed. 

For  the  present  purpose,  the  most  interesting  feature  of  the  inves- 
tigation is  that  these  metabolic  nitrogenous  materials  in  the  fresh  dung 
are  soluble  in  pepsin  hydrochloric  acid,  and  can  thus  be  removed  from 
the  feces,  leaving  a  residue  insoluble  in  pepsin  which  represents  sub- 
stantially the  indigestible  nitrogenous  matter  of  the  feed.  Kellner  ~ 
also  reports  similar  unpublished  results  upon  a  sheep  receiving  non- 
nitrogenous  matter.3  That  this  is  actually  the  case  is  shown  by  com- 
parisons of  the  pepsin-insoluble  nitrogen  in  the  feces  with  that  con- 
tained in  the  feed,  such  as  have  been  made  by  Pfeiffer  and  by  Kiihn. 
The  latter  in  particular  has  shown  that  by  certain  modifications  of 
Stutzer's  method  very  close  agreement  can  be  obtained  between 
artificial  and  natural  digestion  if  the  comparison  in  the  latter  case 
be  made  upon  the  pepsin-insoluble  nitrogen  of  the  feces.  In  other 
words,  the  pepsin-insoluble  nitrogen  of  the  feed  reappears  quan- 
titatively in  the  feces. 

If,  however,  indigestible  bacterial  protein  is  formed  from  (he 
nonprotein  of  the  feed,  this  process  should  increase  the  pepsin- 
insoluble  nitrogen  of  the  feces,  while  if  the  observed  increase  in  (hi* 
fecal  nitrogen  in  some  cases  is  due  to  metabolic  products  these  should 

'Stutzer,  A.  Die  Einwirkung  von  saurem  Magensaft  auf  die  stickstotThnltigan  Bestandthoile  dor 
Mohnkuchen.  Journal  fur  Land wirtschaft,  Jahrgang  liS,  pp.  lftr>  20S.  Berlin,  1SS1. 

Stutzer,  A.  Beitriige  zur  \Yert  hbestimmung  der  Futtermittel.  Journal  fur  Land  wirtschaft,  Jahrgar.g 
28,  pp.  435-453.  Berlin,  1881. 

2  Die  Ernahrung  der  Landwirtschaftliche  Nutztiere,  5th  ed.,  p.  32. 

1  It  is,  of  course,  conceivable  that  the  feces  may  contain  food  nitrogen  which  was  potentially  soluble  but 
which  has  escaped  solution,  but  it  hardly  seems  likely  that  any  such  nitrogen  would  be  dissolved  by  further 
treatment  with  pepsin  in  the  laboratory. 


22 


NUTRITIVE  VALUE   OF    NONPROTEIN    OF   FEEDING   STUFFS. 


be  soluble  in  pepsin.  That  is,  we  may  regard  the  pepsin-insoluble 
nitrogen  of  the  feces  as  representing  indigestible  feed  protein,  and 
the  pepsin-soluble  nitrogen  as  contained  in  metabolic  products,  part 
of  which  are  protein  (mucus,  epithelium,  etc.)  and  part  nonprotein 
(residues  of  digestive  fluids,  etc.).  A  comparison  of  the  pepsin- 
insoluble  nitrogen  in  the  feed  and  feces,  therefore,  affords  the  best 
available  means  of  determining  whether  the  ingestion  of  nonpro- 
tein has  resulted  in  the  formation  of  indigestible  bacterial  protein. 
Such  comparisons  have  been  made  in  the  investigations  by  Morgen 
et  al.,  already  referred  to. 

The  results  of  the  experiments  in  1907  l  include  digestion  experi- 
ments on  3  ewes  in  milk  and  a  partial  report  of  experiments  upon 
2  milch  goats.  The  basis  of  the  ration  consisted  of  dried  sugar  beet 
pulp,  straw,  straw  pulp,  and  a  small  amount  of  hay,  and  contained 
very  little  nonprotein.  To  this  basal  ration  there  were  added  wheat 
gluten,  starch,  oil,  and  sugar.  In  the  experiments  upon  sheep  a 
portion  of  the  protein  supplied  by  the  wheat  gluten  was  replaced  hi 
certain  periods  by  nonprotein  contained  in  an  extract  prepared  from 
malt  sprouts.  Owing  to  the  rather  unpalatable  nature  of  the  rations, 
only  about  three-fourths  of  the  ration  of  the  protein  periods  was  con- 
sumed in  the  nonprotein  periods.  In  the  experiments  with  goats 
the  malt  sprouts  extract  seems  to  have  been  simply  added  to  the  basal 
ration.  The  results  of  these  experiments,  so  far  as  they  relate  to  the 
question  under  discussion,  are  contained  hi  the  following  table: 
Forms  of  nitrogen  in  feed  and  feces — Morgen's  experiments  of  1907. 


Items. 

In  feed. 

In  feces. 

Nonpro- 
tein 
nitrogen. 

Pepsin- 
soluble 
protein 
nitrogen. 

Pepsin- 
insoluble 
nitrogen. 

Nonpro- 
tein 
nitrogen. 

Pepsin- 
soluble 
protein 
nitrogen. 

Pepsin- 
insoluble 
nitrogen. 

Sheep  13: 
Period  1,  protein 

Grams. 
0.81 
5.60 

Grams. 
21.46 
11.14 

-10.  3sr 

Grams. 
0.% 
2.47 

Grams. 
5.24 
5.36 

Grams. 
3.50 
3.39 

Period  2,  nonprotein  
Period  2-period  1 

+4.79 

+  1.51 

+  .12 

-  .11 

Sheep  25: 
Period  1  ,  protein  . 

.69 
3.58 

17.55 
10.21 

1.18 
1.77 

3.95 
3.86 

3.23 
3.07 

Period  3,  nonprotein  
Period  3-period  1  

+2.89 

-  7.34 

+  .59 

-  .09 

-  .16 

Sheep  30: 
Period  1  ,  protein  . 

.69 
1.30 

17. 
9. 

55 
15 

.93 
1.13 

4.78 
2.84 

2.93 
2.87 

Period  3,  nonprotein  
Period  3-period  1  

+  .61 

-8.40 

+  .20 

-1.94 

-  .06 

Goat  28: 
Periods  1  and  5,  basal  
Period  2,  nonprotein  

Period  2-periods  1  and  5.  .  . 

.48 
5.97 

11.70 
12.05 

1.43 
2.94 

3.26 
5.09 

2.45 
3.96 

5.49 

.35 

1.51 

1.83 

1.51 

1  Morgen,  A.,  Beger,  C.,  and  Westhausser,  F.  Weitere  Untersuchungen  iiber  den  Einfluss  der  nicht- 
eiwelssartigen  Stickstofiverbindungen  der  Futtennittel  auf  die  Milchproduktiun.  Die  landwirtschaft- 
Jichen  Versuchs-Stationen,  Band  68,  pp.  333-432.  Berlin,  1908. 


BEHAVIOR   IN    DIGESTIVE   TRACT   OF    HERB1VORA.  23 

Forms  of  nitrogen  in  feed  andfeces — Morgen's  experiments  of  1907 — Continued. 


Items. 


Goat  28— Continued. 

Periods  1  and  5,  basal 

Period  4b,  protein. . . 

Period  4b-periods  1  and  5 . . 

Goat  39: 

Period  1 ,  basal 

Period  3a,  nonprotein 

Period  3a-period  1 ... 


In  feed. 

In  feces. 

Nonpro- 
tein 
nitrogen. 

SSbto     Pe^ln- 

insoluble 
nSen.       »*«*»"• 

Nonpro- 
tein 
nitrogen. 

Pepsin- 
soluble 
protein 
nitrogen. 

Pepsln- 
insoiiible 
nitrogen. 

Oramt. 
0.48 

.55 

Grams. 
11.70 
17.39 

Grams. 
1.43 
1.96 

Grams. 
3.26 
3.  03 

Grams. 
2.45 
3.38 

.07 

5.69 

.53 

-  .23 

.93 

.40 
5.96 

9.50 

9.86 

1.05 
•2.  34 

2.  11 
4.  02 

2.41 
3.26 

5.56 

.36 

.09 

1.91 

.85 

It  appears  from  this  table  that  with  the  goats  the  increase  of  the 
nonprotein  nitrogen  caused  a  distinct  increase  in  the  fecal  nitrogen,  and 
that  of  this  increase  one-fourth  to  one- third  was  insoluble  in  pepsin. 
Since,  however,  the  pepsin-insoluble  nitrogen  of  the  feed  was  not 
determined,  it  is  possible  that  part  of  this  increase  may  have  arisen 
from  a  greater  amount  of  the  latter  in  the  feed;  but  obviously  only 
a  small  part  of  the  increase  in  the  feces  can  thus  be  accounted  for, 
since  the  entire  increase  of  the  protein  nitrogen  of  the  feed  was  only 
0.36  gram,  as  compared  with  0.85  gram  and  1.51  grams  in  the  feces. 
On  the  other  hand,  however,  it  is  to  be  noted  that  there  appears  to 
have  been  a  similar  increase  of  the  pepsin-insoluble  nitrogen  in 
Period  IVb,  in  which  wheat  gluten  instead  of  malt  sprouts  extract 
was  added  to  the  basal  ration. 

In  the  experiments  with  sheep  the  difference  in  the  total  amount  of 
the  ration  noted  above  gives  rise  to  some  difficulty  in  interpreting 
the  results.  It  appears  clear  from  the  table,  however,  that  the 
pepsin-insoluble  nitrogen  of  the  feces  was  practically  unaffected  by 
the  substitution  of  nonprotein  for  protein. 

In  the  investigations  of  1908,1  digestion  experiments  were  made 
on  7  ewes  in  milk,  on  2  milking  goats,  and  on  6  wethers,  the  pepsin- 
insoluble  nitrogen  of  the  feeding  stuffs  being  determined.  The 
experiments  on  the  milk  animals  were  of  the  same  general  nature  as 
those  of  1907  and  the  results  were  similar.  Relatively  more  hay 
was  fed  than  in  the  previous  year,  making  the  rations  more  palatable, 
and  they  were  eaten  without  residue  throughout.  A  considerable 
variety  of  nonprotein-containing  materials  were  used,  viz,  extracts  of 
malts  prouts,  grass,  and  mangels;  ammonium  acetate,  tart arate, and 

1  Morgen,  A.,  Berger,  C.,  and  Westhatisser,  F.  Weitere  rnUTSiichungen  iibor  di<>  Vorwertung  der 
nieht-eiwcissartigen  Stickstoffverbindunpen  der  Futtermittel  sowie  dor  Anunonsalze  (lurch  das  mikh- 
gebende  Tier,  unter  besonderer  Beriicksichtigung  der  stickstoffhallipen  Stoffwechselprodukte.  Die 
Jandwirtschaftlichen  Versuch-Stationen,  Band  71,  pp.  1-170.  Berlin,  1909. 


24 


NUTRITIVE   VALUE    OF    NONPROTEIN    OF    FEEDING   STUFFS. 


phosphate,  and  asparagin.  Each  nonprotein  period  was  interpo- 
lated between  two  protein  "periods,  the  nonprotein  (or  in  two  cases 
carbohydrates)  being  substituted  for  protein.  The  following  table 
gives  the  average  results  obtained  for  each  form  of  nonprotein  com- 
pared with  the  average  of  the  results  with  the  same  animals  for  the 
protein  rations. 

Farms  of  nitrogen  in  feed  andfeces — Morgen's  experiments  of  1908. 


Items. 

In  feed. 

In  feces. 

Non- 
protein 
nitrogen. 

Protein  nitrogen. 

Non- 
protein 
nitrogen. 

Protein  nitrogen. 

Pepsin- 
soluble. 

Pepsin- 
insoluble. 

Pepsin- 
soluble. 

Pepsin- 
insoluble. 

Ammonium  salts: 
Protein  rations  (16  periods) 

Grams. 
0.58 
6.23 

Grams. 
14.77 
8.93 

Grams. 
2.55 
2.33 

Grams. 
0.77 
.86 

Grams. 
3.17 
2.82 

Grams. 
2.91 
2.78 

Ammonium  rations  (9  periods)  . 

Asparagin: 
Protein  rations  (6  periods) 

+5.65 

-  5.84 

-  .22 

+  .09 

-  .35 

-  .13 

.56 
6.19 

14.26 
8.41 

2.48 
2.25 

.73 
.91 

3.18 
2.57 

2.84 
2.56 

Asparagin  rations  (2  periods)  

Carbohydrates: 
Protein  rations  (4  periods) 

+  5.63 

-  5.85 

-  .23 

+  .18 

-  .61 

-  .28 

.60 
.51 

15.45 
9.32 

2.66 
2.48 

.92 
.65 

2.91 
3.41 

2.76 
2.73 

Carbohydrate  rations  (2  periods)  

Malt  sprouts  extract: 
Protein  rations  (4  periods) 

-  .09 

-  6.13 

-  .18 

-  .27 

+  .50 

-  .03 

.64 

7.98 

16.55 
10.91 

2.86 
3.52 

.68 
2.35 

3.31 

5.82 

3.11 
4.69 

Extract  rations  (2  periods)  

Grass  extract: 
Protein  rations  (3  periods)  

+7.34 

-  5.64 

+  .66 

+  1.67 

+2.51 

+  1.58 

.59 
4.32 

15.10 
11.14 

2.60 
3.63 

.84 
1.03 

3.29 
4.26 

2.97 
5.59 

Extract  rations  (1  period)  

Mangel  extract: 
Protein  rations  (2  periods) 

+3.  73 

-  3.96 

+  1.03 

+  .19 

+  .97 

+2.62 

.56 
4.13 

14.26 
11.08 

2.48 
3.42 

.84 
1.05 

2.63 

3.24 

2.84 
4.38 

Extract  rations  (1  period) 

+3.57 

-  3.  18         +  .94 

+  .21 

+  .61 

+  1.54 

The  experiments  with  ammonium  salts  and  asparagin  and  also  the 
substitution  of  carbohydrates  for  protein  resulted  in  a  very  slight 
decrease  of  the  pepsin-insoluble  nitrogen  in  the  feces,  which  was 
closely  paralleled  by  a  similar  decrease  in  the  feed.  In  other  words, 
these  nonprotein  materials  showed  practically  no  effect  upon  the 
fecal  nitrogen.  The  extract  experiments,  on  the  other  hand,  as  in 
the  previous  year's  tests,  showed  a  marked  increase  in  the  pepsin- 
insoluble  nitrogen  of  the  feces,  of  which  increase,  however,  from  40 
to  60  per  cent  is  accounted  for  by  the  increase  in  the  pepsin-insoluble 
nitrogen  of  the  feed.  The  extracts  appear,  therefore,  to  have  had  a 
distinct  effect  in  increasing  the  pepsin-insoluble  nitrogen  of  the  feces. 


BEHAVIOR    IN    DIGESTIVE    TRACT    OF    HERBIVOKA. 


25 


This  increase,  however,  is  much  less  than  that  of  the  total  protein 
nitrogen,  especially  hi  the  case  of  the  malt  sprouts  extract. 

The  digestion  experiments  on  the  wethers  in  this  year  were  intended 
to  test  the  question  whether  the  low  apparent  digestibility  of  the 
protein  of  the  malt  sprouts  extract  as  computed  from  the  foregoing 
digestion  experiments  was  due  to  the  formation  of  indigestible  bac- 
terial protein,  or  to  the  so-called  depression  of  digestion  due  to  the 
small  amount  of  protein  in  the  rations.  To  test  this  question  the 
animals  received  in  the  first  period  only  straw  and  malt  sprouts 
extract,  while  in  period  2  wheat  gluten  was  added  to  this  mixture. 
The  average  result  for  the  four  animals  was  as  follows: 

Forms  of  nitrogen  in  feed  and  feces — Morgeris  experiments  of  1908. 


Items. 

In  feed. 

In  frees. 

Non- 
protein 
nitrogen. 

Protein  nitrogen. 

Non- 
protein 
nitrogen. 

Protein  nitrogen. 

Pepsin- 
soluble. 

Pepsin- 
insoluble. 

Pepsin- 
soluble. 

Pepsin- 
insoluble. 

Period  1,  straw  and  extract... 

Gram*. 
4.1.8 
4.  73 

Grams. 
(i.28 
11.05 

Gram*. 
1.93 
2.  20 

Grams. 
1.33 
1.55 

Grams. 
2.98 
2.  85 

Grams. 
2.99 
2.91 

Period  2,  same  plus  gluten  

Difference 

-.05 

-4.77 

—  .  27 

-.22 

+.  i:{            +.08 

As  compared  with  what  may  be  assumed  to  be  the  normal  results 
in  period  2,  the  straw  and  extract  ration  of  period  1,  containing  much 
less  protein,  showed  nevertheless  on  the  average  a  small  increase  in 
the  protein  nitrogen  of  the  feces,  which,  however,  was  large  enough  to 
be  significant  in  only  two  out  of  the  four  animals  (sheep  F  and  G). 
This  increase  in  the  pepsin-soluble  portion  of  the  fecal  nitrogen  may 
be  taken  to  indicate  that  some  of  the  food  protein  escaped  digestion; 
that  is,  we  have  here  the  so-called  depression  of  digestibility  due  to  a 
relative  excess  of  nonnitrogenous  nutrients.  The  results  computed 
in  this  way  correspond  with  the  digestion  coefficients  as  computed 
by  Morgen. 

In  a  third  period  with  two  of  the  wethers  the  malt  sprouts  ex- 
tract was  replaced  by  starch,  sugar,  and  gluten,  the  amount  of  the 
latter  being  made  approximately  equal  to  the  true  protein  of  the 
malt  extract;  while  in  a  fourth  period,  with  only  one  animal,  wheat 
gluten  equivalent  to  the  total  nitrogen  of  the  malt  sprouts  extract 
was  given.  The  results  were  as  follows: 
95833°— Bull.  139—11 4 


26         NUTRITIVE  VALUE   OF    NONPKOTEIN   OF   FEEDING  STUFFS. 
Forms  of  nitrogen  in  feed  and  feces — Morgen's  experiments  of  1908. 


Items. 

In  feed. 

In  feces. 

K  on  pro- 
tein ni- 
trogen. 

Protein  nitrogen. 

Non  pro- 
tein ni- 
trogen. 

Protein  nitrogen. 

Pepsin- 
soluble. 

Pepsin- 
insoluble. 

Pepsin- 
soluble. 

Pepsin- 
insoluble 

Sheep  C: 
Period  1 

Grams. 
4.80 
.05 

Grams. 
6.60 
6.29 

Grams. 
2.18 
1.74 

Grams. 
1.24 
.34 

Grams. 
2.63 
1.81 

Grams. 
3.41 
2.38 

Period  3    .                       .... 

Period  1-period  3  

4.75 

.31 

.44 

.90 

.82 

1.03 

Sheep  F: 
Period  1  

4.80 
.05 

0.21 
5.51 

1.45 
1.34 

1.05 
.42 

2.79 
1.49 

2.08 
1.65 

Period  3 

Period  1-period  3 

4.75 

.64 

.11 

.03 

1.30 

1.03 

Sheep  T: 
Period  1 

4.80. 
.13 

C.21 
10.31 

1.45 
1.53 

1.05 
.22 

2.79 
1.30 

2.68 
2.12 

Period  4 

Pepiod  1-period  4 

4.  07 

-4.10 

-.08              .S3 

1.43 

.56 

We  see  here  the  same  effect  as  before  of  the  malt  sprouts  extract 
in  increasing  the  total  protein  nitrogen  of  the  feces  and  likewise 
to  a  less  extent  the  pepsin-insoluble  portion  of  it. 

The  experiments  upon  milking  animals  in  1909 l  were  made 
chiefly  with  ammonium  acetate,  which  was  both  substituted  for 
protein  in  the  basal  ration  and  also  added  to  the  latter.  Similar 
addition  experiments  were  also  made  with  grass  extract  and  with  the 
extract  of  dried  sugar-beet  pulp  containing  relatively  much  less  non- 
protein.  The  results  upon  the  different  animals  were,  on  the  whole, 
very  uniform,  and  the  averages  of  the  following  table  appear  sufficient 
to  demonstrate  the  teaching  of  the  experiments: 

Forms  of  nitrogen  in  feed  and  feces — -Morgen's  experiments  of  1909. 


Items. 

In  feed. 

In  fsces. 

Nonpro- 
tein  ni- 
trogen. 

Protein  nitrogen. 

Non  pro- 
tein ni- 
trogen. 

Protein  nitrogen. 

Pepsin- 
soluble. 

Pepsin- 
insoluble. 

Pepsin- 
soluble. 

Pepsin- 
insoluble. 

Ammonium  acetate  added  to  basal  ration 
(7  trials): 
Acetate  ration 

Grams. 
10.73 
.09 

Grams. 
15.72 
15.72 

Grams. 
2.93 
2.93 

Grams. 
1.10 
1.00 

Grams. 
3.16 
3.24 

Grams. 
2.81 
2.83 

Basal  ration  

Difference  

10.04 

.00 

.00 

.04 

-.08 

-  .02 

1  Morgen,  A.,  Beger,  C.,  and  Westhausser,  F.  Untersuchungen  fiber  die  Verwertung  der  Ammonsalze 
und  der  nicht-eiweissartigen  Slickstoffverbindungen  der  Futtermittel  fur  die  Lebenserhaltung  and  Milch- 
bildung,  sowie  fiber  die  Frage.  ob  aus  diesen  Stoffen  unverdatiliches  Eiweiss  gebildet  wird.  Die  land- 
wirtschaftliehen  Versuchs-Stationen,  Band  73,  Heft  4-5,  pp.  285-390.  Berlin,  1910. 


BEHAVIOR   IN   DIGESTIVE   TRACT   OF    HERBIVORA. 


27 


Forms  of  nitrogen  in  feed  andfeces — Morgeri's  experimerits  of  1 909 — Continued. 


Items. 

In  feed. 

In  feces. 

Nonpro- 
tein  ni- 
trogen. 

Protein  nitrogen. 

Nonpro- 
tein  ni- 
trogen. 

Protein  nitropen. 

Pepsin- 
soluble. 

Pepsin- 
insoluble. 

Pepsin- 
soluble. 

Pepsin- 
insoluble. 

Grams. 
2.88 
2.96 

Ammonium  acetate  substituted  in  basal 
ration  (4  trials): 
Acetate  ration  

Grams. 
11.00 
.73 

Grams. 
(i.  14 
16.41 

Grams. 

2.58 
3.06 

Grams. 
1.15 
1.06 

Grams. 
3.08 
3.  23 

Basal  ration     

Difference  

10.27 

-10.27 

-.48 

.09 

-.15 

-.08 

Grass  extract  added  to  basal  ration    (2 
trials): 
Extract  ration  

2.33 

.68 

15.82 
15.44 

3.53 
2.88 

1.09 

.61 

3.  25 
2.81 

4.18 
2.59 

Basal  ration  

Difference  

1.65 

.38 

.65 

.48 

.44 

1.59 

Dried  beet-pulp  extract  added  to  basal 
ration  (2  trials). 
Extract  ration  

1.03 
.68 

15.38 
15.44 

3.23 
2.88 

.95 
.61 

2.  02 
2.81 

3.49 
2.  59 

Basal  ration  

Difference 

.35 

-.06 

.35 

.34 

-.19 

.90 

It  is  clear  that  the  ammonium  salts  produced  practically  no  effect 
upon  the  amount  of  fecal  nitrogen  excreted  in  any  form.  The  grass 
extract,  on  the  other  hand,  shows  the  same  effect  as  in  previous  ex- 
periments, ATiz,  an  increase  of  both  the  protein  nitrogen  and  the 
pepsin-insoluble  nitrogen  of  the  feces,  the  latter  being  greater  than 
can  be  accounted  for  by  the  corresponding  increase  in  the  feed.  On 
the  other  hand,  as  already  noted,  the  beet-pulp  extract,  containing 
much  less  nonprotein  nitrogen,  produced  a  relatively  greater  effect 
in  this  direction,  particularly  as  regards  the  pepsin-insoluble  nitrogen, 
indicating  that  the  result  is  not  caused  Iw  the  nonprotein. 

The  digestion  experiments  of  1909  were  made  upon  4  wethers  with 
the  same  general  plan  and  object  as  in  1908,  viz,  to  test  the  hypothesis 
of  the  formation  of  indigestible  bacterial  protein  from  the  nonprotein. 
In  these  experiments  wheat  gluten  was  added  to  a  basal  ration  con- 
taining little  protein  and  much  nonprotein.  They  differed  from  the 
experiments  of  the  previous  year  in  the  fact  that  the  nonprotein  con- 
sisted of  ammonium  acetate,  which,  as  the  results  on  milking  animals 
just  cited  show,  does  not  produce  indigestible  bacterial  protein.  The 
basal  ration  of  period  1  consisted  of  straw  and  ammonium  acetate. 
The  average  results  for  all  4  animals  were  as  shown  in  the  following 

table : 

Fonits  of  nitrogen  in  feed  and  feces — Morgcn's  experiments  of  HHHI. 


In 


In  ft- 

Protein  nitroircn. 


Periods. 

Xonpro- 

Nimpro- 

toin  ni- 
troircn. 

IVpsin- 
solublc. 

IVnsin- 
insulublc. 

tcin  r.i- 
trogcii. 

IVrxin-       I'cpsir.- 
solubli'.     insuluhlo. 

1 

Grams. 
5.54 

Grams. 
1.41 

Grama. 
1.50 

Gram.'. 

(I.  26 

Cr.?m«.       Gram. 
1.4:'.               !.7S 

2 

5  57 

3  02 

1  .  57 

.  10 

i.4s               1   7S 

3                                     

5.66 

7.53 

1.79 

1.17 

28          NUTRITIVE   VALUE    OF    NONPROTEIN    OF    FEEDING   STUFFS. 

As  in  the  previous  experiments,  the  amount  of  pepsin-insoluble 
nitrogen  in  the  feces  was  practically  unaffected.  On  the  other  hand, 
the  protein  nitrogen  of  the  feces  as  ordinarily  computed  was  much 
less  in  amount  in  period  3,  hi  which  the  larger  quantity  of  gluten 
was  fed,  the  total  amounts  being,  respectively,  in  period  1,  3.21 
grams;  in  period  2,  3.26  grams;  in  period  3,  2.23  grams. 

This  on  its  face  would  indicate  that  some  of  the  food  protein 
escaped  digestion — that  is,  that  there  was  a  so-called  depression  of 
digestibilit}7  in  periods  1  and  2— but  the  excessive  amount  of  non- 
protein  nitrogen  contained  in  the  feces  in  period  3  seems  to  suggest 
the  possibility  of  an  error  in  the  analysis  of  the  latter. 

On  the  whole,  Morgen's  results  seem  to  negative  the  hypothesis 
of  any  considerable  formation  of  indigestible  bacterial  protein  from 
the  nonprotein  of  the  feed.  As  regards  ammonium  salts  and  aspar- 
agin,  they  agree  in  this  respect  with  the  investigations  already  sum- 
marized in  failing  to  show  any  increase  of  either  protein  nitrogen  or 
pepsin-insoluble  nitrogen  in  the  feces.  As  regards  the  extracts  of 
various  feeding  stuffs,  the  results  also  agree  with  the  earlier  results  in 
showing  an  increase  of  the  protein  nitrogen,  but  they  also  strongly 
support  the  conclusion  that  that  increase  is  largely  due  to  the  effect 
of  these  extracts  in  stimulating  the  formation  of  metabolic  products 
and  in  part  also  to  the  fact  that  the  extract  rations  contained  more 
pepsin-insoluble  nitrogen  relatively  than  did  the  rations  with  which 
they  were  compared.  It  should  be  added,  however,  that  practically 
all  of  Morgen's  experiments  show  a  greater  increase  of  pepsin- 
insoluble  nitrogen  in  the  feces  than  can  thus  be  accounted  for, 
although  it  is  not  yet  clear  what  interpretation  is  to  be  placed  upon 
this  fact. 

Finally,  it  should  be  noted  that  these  negative  results  neither 
prove  nor  disprove  the  possibility  of  a  formation  of  digestible  protein 
from  the  nonprotein  of  the  feed. 

NUTRITIVE    VALUE    OF    NONPROTEIN    FOR    HERBIVORA. 

NONPROTEIN    A    SOURCE    OF   PROTEIN. 

In  addition  to  the  earlier  investigations  of  Kellner  and  of  Try- 
niszewski  already  referred  to,  experiments  have  also  been  made  by 
Andrlik,  Velich,  and  Stanek.1  Their  preliminary  trials  showed  that 
betain  injected  into  the  blood  of  a  dog  reappeared  quantitatively  in 
the  urine,  but  that  when  given  by  the  mouth  only  about  one-third 
thus  reappeared,  while  in  a  later  experiment  of  the  same  sort  none 
was  found  in  the  urine.  They  also  failed  to  find  betain  in  the  excreta 

i  Velich,  Alois,  and  Stanek,  Vladimir.  Ueber  das  Betain  in  fysiologischchemischer  Beziehung.  Zweiter 
Bericht.  Zeitschrift  fur  Zuckerindustrie  in  Bohmen,  Jahrgang  29,  Heft  4,  pp.  205-219.  Prag,  1904-1905. 

Andrlik,  K.  and  Velich,  K.  Ueber  die  Bedeutung  dcr  Glutamin-  und  Asparaginsaure  als  Nahrstoffe. 
Zeitschrift  fur  Zuckerindustrie  in  Bohmen,  Jahrgang  32,  Heft  6,  pp.  313-342.  Prag.  1907-1908. 


NONPROTEIX   A   SOURCE   OF    PROTEIN. 


29 


of  a  cow  consuming  considerable  amounts  of  beet  molasses,  a  sub- 
stance relative!}'  rich  in  betain. 

After  these  preliminary  trials,  an  experiment  was  made  on  a 
young  wether  weighing  about  29  kilograms,  including  trials  with 
betain,  glutaminic  acid,  and  aspartic  acid.  The  trials  with  betain 
were  reported  in  1905  and  the  others  in  1908,  but  all  were  made  in 
1904  and  apparently  constituted  a  single  investigation. 

Throughout  the  experiment  the  animal  received  a  basal  ration  of 
500  grams  hay  and  200  grams  wheat  flour  (the  latter  baked  into 
cakes),  with  the  exception  of  periods  4  and  5  of  the  first  series,  in 
which  one-half  of  the  flour  was  replaced  by  starch.  This  ration 
approximates  to  the  maintenance  requirement  of  the  animal  according 
to  the  usual  standards  as  regards  quantity  of  feed,  but  contains  con- 
siderably more  than  the  minimum  of  protein.  The  materials  to  be 
tested  were  simply  added  to  the  basal  ration. 

On  the  average  of  all  the  periods  the  basal  ration  contained  per 
day  and  head: 

Grams. 

Total  nitrogen 5.  05 

Protein  nitrogen 4.  1  •> 

In  the  nonprotein  periods  the  amounts  of  nitrogen  added  in  the 
various  forms  were : 

G  ranis. 

In  betain 2.  21 

In  glutaminic  arid ].  915 

In  aspartic  acid 2.  11 

In  the  first  series  of  trials  the  periods  were  short,  covering  only 
5  or  6  days  with  either  one  or  no  intermediate  days.  In  the  second 
series  the  periods  extended  over  from  14  to  18  days,  all  of  which, 
however,  are  included  in  the  averages  compared. 

Computed  in  this  manner,  the  gain  or  loss  of  nitrogen  by  the 
animal  was  as  follows : 

Gain  or  loss  of  nitrogen — Andrlik,  Velich,  and  Stan ek' s  experiments. 


Items. 

Oain(  +  ) 
or  loss  (—  ). 

Items. 

Oain  (  +  ) 
or  loss  (  —  ). 

Series  I: 
Period  1  ,  basal  ration  

Grams. 
+  1.14 

Series  II: 
I  eriod  1, 

basal  ration 

Gram*. 
+  0.  97 

Period  2,  betain  

+  1.22 

1  eriod  2, 

L'lul  :un  ill  !<•  arid  

+  1  .  27 

Period  3,  basal  ration 

+  .71 

I  eriod  3, 

basal  ration 

+     9<> 

Period  4,  betain 

+  .92 

1  eriod  4, 

aspartic  acid  

+  1.90 

Period  5,  basal  ration 

—  .42 

I  eriod  5, 

basal  ration 

+     ''7 

Omitting  periods  4  and  5  of  Series  I,  in  which  the  nitrogen  content 
of  the  basal  ration  was  reduced,  we  may  compute  the  following 
averages  apparently  showing  that  the  nitrogenous  substances  added 
were  at  least  partially  utilized  in  the  body  of  the  animal: 


Gram. 


For  the  basal  ration +0.  90 

For  the  nonprotein  ration -f-1.  46 


30 


NUTRITIVE   VALUE    OF    NONPROTEIN    OF    FEEDING    STUFFS. 


The  principal  evidence  regarding  the  nutritive  value  of  nonprotein 
for  herbivora,  however,  is  derived  from  later  experiments  by  Kellrier 
on  lambs  and  cows,  from  the  investigations  by  Morgen  et  al.,'  whose 
results  as  regards  the  behavior  of  nonprotein  in  the  digestive  tract 
have  just  been  discussed,  and  from  experiments  by  the  Laboratory 
for  Agricultural  Research  in  Copenhagen. 

Kellner  1  experimented  on  lambs  in  the  belief  that  growing  animals 
would  furnish  the  most  favorable  conditions  for  the  utilization  of 
nonprotein.  After  a  vain  attempt  to  use  rations  containing  ammo- 
nium acetate  or  asparagin  as  the  sole  source  of  nitrogen,  he  succeeded 
in  finding  three  animals  which  consumed  sufficient  amounts  of  a 
ration  consisting  of  starch,  sugar,  ash,  asparagin,  and  ammonium 
acetate,  together  with  300  to  400  grams  of  straw,  to  enable  the  experi- 
ment to  be  carried  through.  This  ration  contained,  of  course,  a 
minimum  of  digestible  protein.  In  a  second  period  the  ammonium 
acetate  and  asparagin  were  replaced  by  wheat  gluten  nearly  equiva- 
lent in  nitrogen  content,  and  in  the  case  of  two  of  the  animals  a  tlu'rd 
period  was  employed  in  which  ammonium  acetate  and  asparagin 
equal  to  that  consumed  in  the  first  period  were  added  to  the  ration 
of  the  second  period.  The  energy  content  of  the  rations  was  main- 
tained constant  by  varying  the  amounts  of  starch  and  sugar. 

Regarding  the  pepsin-soluble  nitrogen  of  the  straw  as  the  measure 
of  its  digestible  protein,  and  counting  all  the  small  amount  of  nitroge- 
nous matter  in  the  starch  as  digestible,  the  total  content  of  protein  of 
the  basal  rations  was  far  below  the  maintenance  requirement  of  0.4 
kilogram  protein  per  1,000  kilograms  live  weight,  as  appears  from 
the  following  table: 1 

Digestible  protein  in  basal  rations— Kellner' s  experiments. 


Series  and  periods. 

Per  head. 

Per  1,000 
kilograms 
live  weight. 

Series  I: 
Period  1  -*r  

• 
Grams. 

4.  70 

Kilos. 
0.  11 

Period  2  

4.44 

.  10 

Series  II: 
Period  1                                                    

5.34 

.  11 

Period  2 

4.91 

.  10 

Period  3  

4.91 

.  10 

These  experiments  have  already  been  considered  in  their  bearings 
upon  the  fate  of  the  nonproteins  in  the  digestive  tract  (p.  18), 
The  results  as  to  the  production  of  flesh  are  shown  in  the  following 
table  of  the  nitrogen  balances  per  day  and  head: 

1  Kellner,  O.,  Eisenkolbe,  P.,  Flebbe,  R.,  and  Neumann,  R.  Untersuchungen  iiber  den  Einfluss  einiger 
nicht-eiweissartiger  Stickstoffverbindungen  auf  den  Eiweissumsatz  beim  Weiderkauer.  Die  landwirt- 
schaftlichen  Versuchs-Stationem,  Band  72,  Heft  5-C,  pp.  437-458.  Berlin,  1910. 

1  The  approximate  live  weights  were  44  kilograms  in  the  first  series  and  48  kilograms  in  the  second  series. 


NONPROTEIN   A   SOURCE   OF   PROTEIN. 
Nitrogen  balances — Kellner's  experiments. 


31 


Items. 

Period  I. 

Period  II. 

Period  III. 

Totiil 
nitrogen. 

Protein 
nitrogen. 

Total 
nitrogen. 

Protein 
nitrogen. 

Total 
nitrogen. 

Protein 
nitrogen. 

Series  I: 
Lamb  1— 
In  feed  

Grams. 
12.  19 

Grams. 

1.18 

Grams. 
11.  11 

Grams. 
10.  19 

Grams. 

Grams. 

In  feces  

6.73 
5.37 

4.20 

4.92 
4.26 

4.25 

In  urine  

In  total  excreta  

12.  10 

9.  18 

Gain  

+  .09 

+  1.93 

Series  II: 
Lamb  2— 
In  feed          

15.82 

1.55 

12.86 

11.74 

26.51 

11.62 

In  feces  

5.08 
10.  16 

4.37 

5.  <•  1 
4.28 

4.50 

5.51 
16.  17 

4.48 

In  urine  

In  total  excreta  

15.24 

10.22 

21.68 

Gain  

+  .58 

+2.64 

+  4.83 

Lamb  3  — 
In  feed 

15.82 

1.55 

12.84 

11.72 

26  51 

11.62 

In  feces  

tv  IIS 

10.70 

4.92 

6.  19 
5  13 

4  :u 

5.17 
16.  72 

4.73 

In  urine  

In  total  excreta  

17.38 

11.32 

22.69 

Gain  

—  1.56 

+  1.52 

+3.82 

Two  general  conclusions  seem  to  follow  from  the  foregoing  results: 

First,  there  appears  to  be  clear  evidence  of  a  conversion  of  non pro- 
tein into  protein.  Although  the  amount  of  true  protein  in  the  feed 
in  Period  I  was  about  one-fourth  that  required  for  maintenance, 
lamb  1  was  fully  maintained  and  lamb  2  showed  a  small  gain  of  nitro- 
gen, while  in  case  of  lamb  3  the  protein  lost  from  the  body  plus  that 
supplied  in  the  feed  amounts  to  only  14.66  grams  protein  per  head, 
equivalent  to  0.31  kilogram  per  1,000  kilograms  live  weight,  or  about 
three-fourths  of  the  maintenance  requirement.  Moreover,  the  non- 
protein  added  in  Period  III  to  the  ration  of  Period  II  caused  a  notable 
increase  in  the  storage  of  protein  in  the  body,  either  directly  or  In- 
taking  the  place  of  protein  previously  used  for  maintenance  purposes. 

Second,  the  nonprotein  was  clearly  inferior  to  protein,  for  the 
substitution  of  the  latter  for  the  former  in  Period  II  caused  a  notable 
gain  of  protein  by  the  animals  in  place  of  approximate  maintenance, 
even  although  the  supply  of  total  nitrogen  in  the  feed  was  less  than 
in  Period  I  in  every  case  and  that  of  digestible  nitrogen  less  in  two 
cases  out  of  the  three. 

Kellner's  conclusion  is  that  the  ammonium  salts  and  asparagin 
were  synthesized  by  the  bacteria  of  the  digestive  tract  to  more  com- 
plex nitrogenous  compounds,  possibly  even  to  proteins,  and  that  these 
compounds  were  subsequently  digested  and  served  in  Period  I  to 
maintain  the  protein  of  the  body.  The  striking  difference  between 
the  results  of  Period  I  and  those  of  Period  II  he  regards  as  showing 


32          NUTRITIVE   VALUE    OF    NONPROTEIN    OF    FEEDING   STUFFS. 

that  while  nonprotein  may  thus  indirectly  perform  maintenance 
functions  it  is  incapable  of  causing  actual  growth  of  protein  tissue. 
The  increased  gain  observed  in  Period  III  he  explains  in  the  manner 
previously  indicated,  viz,  that  the  nonprotein  was  substituted  for 
protein  for  maintenance  purposes. 

But  while  this  explanation  is  consistent  with  the  experimental 
results,  the  existence  of  such  a  marked  distinction  between  digested 
feed  protein  and  digested  products  of  bacterial  synthesis  appears  to 
the  writer  unlikely.  We  can  scarcely  imagine  that  this  synthesis 
should  result  in  the  production  of  any  simpler  compounds  than  the 
simple  amino  acids,  while  it  is  more  likely  to  extend  at  least  to  the 
formation  of  polypeptids  if  not  in  part  to  that  of  proteins.  It  is 
well  established,  however,  that  substantially  these  comparatively 
simple  substances  constitute  the  nitrogenous  food  of  the  body,  and 
it  is  not  apparent  why  their  origin  through  bacterial  synthesis  should 
render  them  any  less  available  than  similar  substances  resulting  from 
enzym  cleavage  of  feed  protein.  While  minor  differences  may  exist, 
it  appears  more  probable  that  the  limit  to  the  nutritive  value  of  non- 
proteins  to  the  herbivorous  animal  is  set  by  the  amount  which  the 
bacteria  are  able  to  synthesize  rather  than  by  a  difference  in  the 
value  of  the  products,  and  this  belief  seems  to  be  supported  by  the 
investigations  at  the  Hohenheim  Experiment  Station  by  Morgen 
et  al.  upon  milk-producing  animals  (sheep  and  goats),  about  to  be 
considered. 

The  results  of  Morgen's  investigations  have  already  been  dis- 
cussed in  their  bearing  upon  the  fate  of  nonprotein  in  the  digestive 
tract,  but  the  digestion  experiments  cited  for  this  purpose  formed  only 
part  of  more  extensive  investigations,  including  numerous  additional 
animals,  in  which  the  yield  and  composition  of  the  milk  produced 
were  determined. 

Perhaps  the  most  striking  result  of  these  investigations  is  the 
demonstration  that  nonprotein  nitrogen  in  the  form  of  ammonium 
salts  or  asparagin  is  capable  of  contributing  to  the  production  of 
milk  protein.  This  conclusion  is  based  upon  a  comparison  of  the 
milk  protein  with  the  digestible  true  protein  of  the  feed,  the  latter 
being  considered  equivalent  to  the  protein  nitrogen  of  feed  minus 
protein  nitrogen  of  feces.  At  first  thought  it  might  seem  that  only 
the  pepsin-insoluble  nitrogen  of  the  feces  should  be  considered  in 
this  calculation,  since  there  is  good  reason  to  believe  that  the  re- 
remainder  of  the  fecal  nitrogen  is  present  as  metabolic  products. 
But  while  this  is  probably  true,  on  the  other  hand  these  nitrogenous 
metabolic  products,  so  far  as  they  are  protein  in  nature  (mucus,  epi- 
thelium, etc.),  constitute  a  loss  of  protein  from  the  body,  and  there- 
fore should  be  taken  into  account  in  drawing  conclusions  from  the 
nitrogen  balance. 


NONPROTEIN    A   SOURCE   OF   PROTEIN. 


33 


In  the  experiments  of  1907 !  upon  malt  sprouts  extract,  the  diges- 
tion experiments  whose  results  have  already  been  cited  (p.  22) 
included  also  determinations  of  the  urinary  nitrogen  and  of  the  nitro- 
gen in  the  daily  growth  of  wool.  Assuming,  on  the  basis  of  earlier 
experiments,  a  maintenance  requirement  of  0.4  kilogram  digestible 
protein  per  1,000  kilograms  live  weight  (an  estimate  corresponding 
almost  exactly  with  Katayama's  results2),  they  compute  the  amount  of 
protein  available  per  day  and  head  for  milk  production  in  the  periods 
in  which  nonprotein  was  partially  substituted  for  protein  as  follows: 

Protein  available  for  milk  production — Morgen's  experiments  of  1907. 


Items. 

Sheep  13, 
period  2. 

Sheep  2"), 
period  3. 

Coat  2S, 
period  2. 

Goat  39, 
period  3a. 

Protein  nitrogen  available  

Grams. 
2.39 

Grams. 
3.28 

Gram.?. 
3  00 

Grams. 
•         2  58 

Estimated  for  maintenance  

2.88 

2.37 

2.37 

2.  56 

Remainder  

—     49 

91 

ti3 

02 

In  growth  of  woo!  

.79 

.04 

Remainder. 

—  1  28 

27 

03 

02 

Loss  from  bodv.  .  .  . 

1  02 

1  89 

1  53 

1  39 

Availablp  for  milk 

26 

2    Iti 

2  Hi 

1    41 

Found  in  mil  k  .  . 

2  29 

2  70 

3  71 

2  83 

Deficit  

2  55 

54 

1  55 

!  42 

Nonprotein  nitrogen  in  feed  

5.  IX) 

3  58 

5.97 

5  % 

Utilization  of  nonprotein.  . 

Per  cent. 
45  54 

Per  cent. 
15  08 

Per  cent. 
•>5  go 

Per  cent. 
•'3  83 

In  every  instance  the  milk  contained  more  protein  than  was  com- 
puted to  be  available  from  feed  and  body  protein,  while  in  the  extreme 
case  (sheep  13)  the  feed  protein  was  little  more  than  equal  to  the 
milk  protein  plus  wool  protein,  leaving  only  0.33  gram  protein  nitro- 
gen for  maintenance.  Evidently  the  nonprotein  must  have  been 
utilized  either  for  the  production  of  milk  protein  or  for  the  mainte- 
nance of  the  body  tissues.  In  the  comparison  periods  in  which  protein 
instead  of  nonprotein  was  fed,  on  the  other  hand,  the  amount  of 
protein  available  for  milk  production,  computed  in  the  same  manner, 
was  considerably  in  excess  of  the  protein  found  in  the  milk.  In 
general,  then,  the  results  of  this  series  of  experiments  correspond 
with  those  obtained  in  Kellner's  experiments  on  lambs. 

The  experiments  of  1908 3  included  two  trials  on  malt  sprouts 
extract,  one  each  upon  grass  extract  and  mangel  extract,  eight  upon 
ammonium  acetate,  one  upon  ammonium  tartrate,  and  two  upon 

1  Morgen,  A.,  Berger,  C.,  and  Westhausser,  F.  Woitrrc  Untersuchungon  iil>or  don  Kinfluss  dor  nicht- 
eiweissartigen  Stickstoffverbindungen  der  Futtcrmittcl  auf  die  Milchproduktion.  Die  landwirtschaft- 
lichen  Versuchs-Stationcn,  Jahrpang  68,  Hoft  5-fi,  pp.  333-432.  Berlin,  1908. 

*  Katayama,  T.  Uber  das  Eiweiss-Minimum  fur  ausgewachscne  Hammcl.  Die  landwlrtschaftlicnen 
Versuchs-Stationen,  Band  69,  Heft  5-6,  pp.  321-341.  Berlin,  1908. 

'Morgen,  A.,  Beger,  C.,  and  Westhausser,  F.  Weitere  Untersuchungen  iilx?r  die  Verwertung  der 
nicht-eiweissartigen  Stickstoffverbindungen  der  Futtetmittel  sowie  der  Ammonsalze  durch  das  milch- 
gebende  Tier  unter  besonderer  Beriicksichtigung  der  stickstoffhaltigen  Stoffwechselprodukte.  Die  land- 
wlrtschaftlichen Versuchs-Stationen,  Band  71,  Heft  1-3,  pp.  1-170.  Berlin,  1909. 


34 


NUTRITIVE  VALUE   OF    NONPROTEIN   OF   FEEDING   STUFFS. 


asparagin,  in  all  of  which  the  nitrogen  balance  was  determined.1 
Computed  as  before,  the  average  results  per  day  and  head  for  each 
nonprotein  material  were  as  follows: 

Protein  available  for  milk  production — Morgen's  experiments  of  1908. 


Items. 

Ammo- 
nium 
salts. 

Aspara- 
gin. 

Extract 
of  malt 
sprouts. 

Extract 
of  grass. 

Extract 
of  man- 
gels. 

Protein  nitrogen  available           

Grams. 
5.09 

Grains. 
5  53 

Grams. 
3  93 

Grams. 
4  92 

Grams. 
6  88 

Estimated  for  maintenance  

2.57 

2  50 

3.14 

2.62 

2.50 

Remainder  .         

3.12 

3  03 

79 

2  30 

4  38 

In  growth  of  wool  

.47 

.54 

.70 

.48 

Remainder  

2.65 

2.49 

.09 

1  82 

4  38 

Loss  from  body  

.18 

—  .01 

2.28 

.75 

—     49 

Available  for  milk  

2.83 

2.48 

2.37 

2  57 

•3  89 

Found  in  milk  

4.21 

3.92 

3.95 

2.17 

3.51 

Deficit.               

1.38 

1.44 

1.58 

Nonprotein  nitrogen  in  feed 

6  23 

6  19 

7  98 

Per  cent. 
22  15 

Per  cent. 
23  26 

Per  cent. 
19  80 

Per  cent. 

Per  cent. 

All  the  experiments,  except  the  single  trials  upon  extracts  of  grass 
and  of  mangels,  showed  a  deficit  of  available  protein  as  compared 
with  the  amount  found  in  the  milk,  while,  as  in  1907,  the  comparison 
periods  in  which  protein  was  fed  showed  a  surplus.  The  exceptional 
results  with  the  two  extracts  may,  perhaps,  be  ascribed  to  the  fact 
that  in  these  trials  a  smaller  proportion  of  the  digestible  protein  was 
replaced  by  nonprotein  than  in  the  other  cases  (about  21  per  cent 
as  compared  with  33  to  38  per  cent),  although  the  replacement  was 
carried  as  far  as  in  the  experiments  with  sheep  in  1907. 

The  experiments  of  1909  2  showed  even  more  striking  results  in  the 
four  cases  in  which  about  63  per  cent  of  the  digestible  true  protein 
was  replaced  by  ammonium  acetate.  The  individual  results,  per  day 
and  head,  computed  as  in  the  preceding  cases,  were : 

Protein  available  for  milk  production — Morgan's  experiments  of  1909. 


Items. 

Sheep  48, 
period  2. 

Sheep  49, 
period  2. 

Sheep  50, 
period  2. 

Sheep  56, 
period  3. 

Protein  nitrogen  available 

Grams. 
2.89 

Grams. 
2.73 

Grams. 
2  70 

Grams. 
2.70 

Estimated  for  maintenance  and  wool  

3.55 

3.67 

3.35 

3.33 

Remainder  .                  .             

—  .06 

-     94 

—  .05 

-  .(>3 

Loss  from  body  

—  .16 

.24 

—  .45 

-  .27 

Available  for  milk  

-  .82 

-  .70 

-1.10 

-  .90 

Found  in  milk 

4  15 

3  61 

3  55 

3.19 

Total  deficit 

4  97 

4  31 

4.65 

4  09 

Nonprotein  nitrogen  in  feed  

11  65 

11.65 

10.35 

10.35 

Utilization  of  nonprotein    

Per  cent. 
42.7 

Per  cent. 
37.0 

Per  cent. 
44  9 

Per  cent. 
39.5 

i  The  results  as  regards  digestibility  are  tabulated  on  page  24. 

»  Morgen,  A.,  Beger,  C.,  and  Westhausser,  F.  Untersuchungen  iiber  die  Verwertung  der  Ammonsalze 
und  der  nicht-eiweissartigen  Stickstoffverbindungen  der  Futtermittel  fur  die  Lebenserhaltung  und  Milch- 
bildung,  sowie  iiber  die  Frage  ob  aus  diesen  Stoffen  unverdauliches  Eiweiss  gebildet  wird.  Die  land- 
wirtschaftlichen  Versuchs-Stationen,  Band  73,  Heft  4-5,  pp.  285-396.  Berlin,  1910. 


NONPROTEIN   A   SOURCE   OF   PROTEIN. 


35 


The  only  conclusion  which  can  be  drawn  from  these  results  is  that 
the  ammonium  acetate  served  as  a  source  of  milk  protein.  Any 
error  in  the  estimate  of  the  maintenance  requirement  is  without  sig- 
nificance, since,  even  if  we  disregard  the  slight  gain  of  protein  by  the 
body  in  three  cases,  the  total  amount  of  protein  contained  in  the 
rations  (plus  that  supplied  from  the  body  by  sheep  49)  is  notably  less 
than  the  amount  actually  found  in  the  milk.  The  obvious  interpre- 
tation of  these  results  is  that  some  of  the  ammonium  acetate  was 
synthesized  to  protein  by  means  of  bacteria  and  subsequently 
digested. 

On  the  other  hand,  the  seven  trials  in  which  ammonium  acetate  was 
added  to  a  basal  ration  containing  a  moderate  amount  of  digestible 
protein,  instead  of  being  substituted  for  the  latter,  yielded  no  such 
results,  the  true  protein  present  being  more  than  sufficient  for  all 
purposes.  The  same  thing  was  likewise  true  of  the  trials  in  which 
extracts  of  grass  and  of  dried  beet  pulp  were  added  to  the  basal  ration. 

A  similar  result  has  also  been  reported  by  Kellner  l  in  an  experi- 
ment on  a  milch  cow.  The  protein  content  of  the  ration  was  gradu- 
ally diminished  until  the  excess  over  the  maintenance  requirement 
was  practically  equal  to  the  protein  of  the  milk,  and  then  a  part  of 
the  remaining  protein  was  replaced  by  ammonium  acetate  and  starch, 
the  total  ration  in  both  cases  being  sufficient  to  cause  some  gain  of 
body  fat.  The  results  as  regards  nitrogen  were  as  follows: 

Protein  available  for  milk  production — Kellner' s  experiments. 


Items. 

Period  VI, 
with 
ammonium 
acetate. 

Period  VII, 
without 
ammonium 
acetate. 

Protein  nitrogen,  digested  

Gram*. 
22.23 

Grams. 
53.83 

Estimated  for  maintenance  

28.98 

28.98 

—  6.75 

24  85 

—  1  % 

4-   1  8t> 

Available  for  milk           .                                         .                 

1    7'.! 

22  99 

In  milk                                                             

53.  37 

55.79 

Deficit  .  .              

58.  1C. 

32.80 

<i2  (XT 

34  70 

Utilization  of  nonprotcin                                               

Vtr  cent. 
93.  7fi 

t'rr  cent. 
94.52 

Even  in  Period  VII  there  appears  to  have  been  a  slight  formation  of 
milk  from  the  nonprotein  of  the  feed,  while  in  Period  VI  the  phenom- 
enon is  even  more  striking  than  in  Morgen's  experiments.  Kellner, 
it  is  true,  has  subsequently  2  expressed  the  opinion  that  his  results 
do  not  prove  such  a  utilization  of  nonprotein,  since  it  is  uncertain 


1  Kellner,  Oskar.     Die  Ernii lining  der  Land wirtschaf ten  Nutrtiere,  4th  ed.,  p.  539. 
1  Kellner,  Oskar.    Ibid.,  5th  ed..  p.  549. 


36 


NUTRITIVE  VALUE   OF    NONPROTEIN    OF   FEEDING  STUFFS. 


how  much  of  the  indigestible  protein  found  in  the  feces  may  have 
been  bacterial  protein  derived  from  the  nonprotein  of  the  feed.  As 
has  been  shown  in  the  foregoing  pages,  however,  the  evidence  is 
strongly  against  such  an  action  in  the  digestive  tract,  and  it  would 
seem  that  Kellner's  results  must  rank  with  Morgen's  as  showing 
a  possible  utilization  of  ammonia  for  the  production  of  milk  protein. 
Experiments  upon  the  minimum  protein  requirements  of  dairy 
cows  reported  from  the  Laboratory  for  Agricultural  Research  in 
Copenhagen  in  1906-7  l  afford  confirmation  of  Morgen's  results.  In 
these  experiments  the  cottonseed  cake  contained  in  the  initial  ration 
was  gradually  withdrawn,  while  the  amount  of  fodder  beets  was 
increased  so  as  to  maintain  unchanged  the  number  of  feed  units  in  the 
ration  computed  according  to  Fjord's  system.  The  protein  nitrogen 
of  the  ration  was  thus  largely  reduced  while  the  amount  of  nonprotein 
shows  but  slight  differences.  The  experiments,  therefore,  show  little 
as  to  the  behavior  of  nonprotein  in  the  digestive  tract  or  as  to  its 
nutritive  value  as  compared  with  that  of  protein.  Like  Morgen's 
experiments  of  1907  and  1908,  however,  they  appear  to  show  that  the 
nonprotein  of  the  rations  must  have  served  at  least  for  the  mainte- 
nance of  the  protein  tissues  of  the  body,  while  in  some  instances  the 
assumption  of  a  small  formation  of  milk  protein  from  nonprotein 
seems  necessary.  The  following  table,  compiled  from  the  Sixtieth 
Report,  shows  the  results  of  those  of  the  experiments  in  which  the 
smaller  amounts  of  true  protein  were  consumed.  On  the  average  of 
all  these  trials,  the  nonprotein  nitrogen  constituted  about  23  per  cent 
of  the  total  nitrogen.  The  table  shows  that  in  general  the  protein 
available  from  the  feed,  plus  that  contributed  by  the  body  protein, 
is  approximately  equal  to  the  milk  protein,  so  that  the  maintenance 
function  at  least  must  have  been  supported  by  the  nonprotein. 

Results  of  Copenhagen  experiments — Sixtieth  Report. 


Pro- 

tein 

Per- 

Items. 

Pro- 
tein 
nitro- 
gen 
digest- 
ed.2 

Gain 
of 
nitro- 
gen 
by 
body. 

nitro- 
gen 
avail- 
able 
for 
milk 

Nitro- 
gen in 
milk. 

..  Sur- 
plus 
for 
mainte- 
nance. 

mated 
mainte- 
nance 
re- 
qu  ire- 

Deficit 
of  pro- 
tein 
nitro- 
gen. 

Non- 
protein 
nitro- 
gen in 
feed. 

centage 
utiliza- 
tion of 
non- 
protein 
nitro- 

produc- 

gen. 

tion. 

Cow  No.  10: 

Grams. 

Grams. 

Grams. 

Grams. 

Grams. 

Grams. 

Grams. 

Per  ct. 

Per  ct. 

Period  4 

47 

—16 

63 

63 

0 

32 

32 

35 

91.4 

Period  5  . 

44 

—12 

56 

60 

—4 

32 

36 

36 

100.0 

Period  6.     ... 

57 

—  2 

59 

62 

—3 

32 

35 

39 

89.7 

Cow  No.  23: 

Period  4 

47 

—  9 

56 

59 

3 

35 

38 

34 

111.8 

Period  5  ... 

47 

-15 

62 

57 

5 

35 

30 

36 

83.3 

1  Denmark — Beretning  fra  den  Kgl.    Vetennaer  of  Landbohojskoles  Laboratorium  for  landokonom 
iske  Forsog.    60de,  1906,  and  63de,  1907,  Kobenhavn.    Translated  by  Mallevre,  Societe  de  1' Alimentation 
Rationale  du  Be1  tail.    Compie  Rendu  de  lleme  et  12eme  Congres. 

2  Protein  nitrogen  of  feed  minus  protein  nitrogen  of  feces. 


NONPROTEIN    A   SOURCE    OF   PROTEIN. 
Results  of  Copenhagen  experiments — Sixtieth  Report — Continued. 


Pro- 

tein 

Items. 

Pro- 
tein 
nitro- 
gen 
digest- 
ed. 

Gain 
of 
nitro- 
gen 
by 
body. 

nitro- 
gen 
avail- 
able 
for 
milk 
produc- 

Nitro- 
gen in 
milk. 

Sur- 
plus 
for 
mainte- 
nance. 

mated 
mainte- 
nance 
re- 
quire- 
ment. 

Deficit 
of  pro- 
tein 
nitro- 
gen. 

Non- 
protein 
nitro- 
gen in 
feed. 

tion. 

Cow  No.  53: 

Grams. 

Grams. 

Grams. 

Grams. 

Grams. 

Grams. 

Grains. 

Perct. 

Period  4  . 

53 

—  2 

55 

50 

—  1 

30 

31 

34 

Period  5  . 

28 

-13 

41 

45 

_4 

30 

34 

39 

Period  6. 

50 

+  3 

47 

49 

30 

32 

41 

Cow  No.  08: 

Period  4  

rj 

02 

03 

—  1 

32 

33 

35 

Period  5  

44 

-10 

IK) 

58 

2 

32 

30 

30 

'    Period  14  

48 

50 

50 

0 

32 

32 

33 

Cow  No.  58: 

Period  4  . 

51 

j 

52 

52 

0 

32 

32 

34 

Period  5  . 

27 

-13 

40 

45 

32 

37 

37 

Period  0. 

+  0 

49 

47 

2 

32 

30 

3s 

Total  

055 

-97 

752 

700 

—  14 

448 

402 

507 

37 


Per- 
centage 
utiliza- 
tion of 
non- 
protein 
nitro- 
gen. 


Perct. 
91.2 

S7.2 
7H.  1 

94.3 
S3.  3 


!)4.  1 
100.0 

7S.  9 

91.1 


In  the  experiments  recorded  in  the  Sixty-third  Report  the  fact  is 
taken  into  account  that  a  portion  of  the  nitrogen  of  the  beets  existed 
in  the  form  of  nitrates,  which,  as  is  well  known,  yield  free  nitrogen 
in  the  digestive  tract.  For  this  reason  the  loss  of  protein  from  the 
body  is  somewhat  greater  than  that  which  would  be  computed  from 
the  income  and  outgo  of  nitrogen  in  the  usual  way.  When  the  results 
of  the  experiments  are  computed  after  the  ordinary  method,  they 
show  in  several  cases  a  distinct  deficit  of  protein;  that  is,  the  protein 
available  from  the  food  plus  that  contributed  by  the  body  is  dis- 
tinctly less  than  the  protein  of  the  milk.  When  the  correction  for 
nitrates  is  applied,  however,  these  differences  either  disappear  or 
become  almost  negligible,  as  is  shown  by  the  following  table: 

Results  of  Copenhagen  experiments— Sixty-third  Report. 


Pro- 

tein 

Per- 

Items. 

Pro- 
tein 
nitro- 
gen 
digest- 
ed. 

Gain 
of 
nitro- 
gen 

bodv. 

nitro- 
gen 
avail- 
able 
for 
milk 

Nitro- 
gen in 
milk. 

Sur- 
plus 
for 
mainte- 
nance. 

uited     Delicit 
i   ainto-  of  pro- 
ancc  ,    tein 
re-        nitro- 
<  uiro-       gen. 

Son-     M'JJIJ^" 

produc- 

gen. 

tion. 

Cow  No.  68: 

Gram*. 

Grams. 

Grams. 

drama. 

dram.".    Crams. 

Grams. 

Grams. 

I'er  cl. 

Period  3 

57 

—  10 

73 

65 

8              30              22              35            02.9 

Period  4  . 

-20 

59 

59 

30              30              35            S.V  7 

Period  5  

30           -23 

53 

30              35              30            '.17.2 

Period  0                              '         53         —  4 

59 

30              32              39            S2.  \ 

Cow  No.  125: 

Period  4  .                           .           09         —  1  7 

SO 

S3 

33              30              55            51.0 

Periods                                     09        —12 

81 

83 

—                33             35             54           04.8 

Period  0.                                      s7         4-4 

83 

79 

4              33              29              .">.">            5'>.  7 

Period  7 

94 

+  7 

87 

79 

8             33 

25 

54 

40.3 

38         NUTRITIVE  VALUE   OF    NONPROTEIN   OF   FEEDING   STUFFS. 

EFFECT   OP    NONPROTEIN    ON    TOTAL   PRODUCTION. 

But  while  Morgen's  results  on  milking  animals  differ  from  Kellner's 
on  lambs  in  this  one  point,  their  results  are  entirely  in  accord  in  show- 
ing that  the  nutritive  value  of  nonprotein  is  much  inferior  to  that  of 
protein.  This  becomes  apparent  as  soon  as  we  turn  from  a  study 
of  the  digestion  trials  and  nitrogen  balances  to  a  consideration  of 
the  actual  yield  of  milk  and  its  constituents  on  the  various  rations. 
The  preliminary  experiments  of  1906  l  showed  a  marked  decrease 
in  the  milk  production  when  nonprotein  was  substituted  for  protein, 
and  the  more  elaborate  experiments  of  the  following  years  only 
confirmed  this  result. 

The  experiments  were  made  after  the  so-called  "period  system," 
the  natural  decrease  in  the  milk  yield  with  advancing  lactation 
being  estimated  by  a  comparison  between  an  initial  and  a  final 
period  on  identical  rations.  In  comparing  his  results  Morgen  simply 
adds  the  correction  thus  computed  for  each  period  to  the  observed 
yield,  and  thus  computes  what  the  yield  would  have  been  had  there 
been  no  depression  due  to  advancing  lactation,  and  these  corrected 
numbers  constitute  the  basis  for  comparing  the  effects  of  the  rations. 
It  may  easily  be  shown,  however,  that  this  method  of  computation 
is  incorrect  and  tends  to  reduce  the  real  effects  of  the  changes  in  the 
rations.  For  example,  in  one  experiment  the  average  daily  yields 
of  milk  solids  were: 

Grams. 

Period  1,  protein  ration 105.  70 

Period  2,  malt  sprouts  extract  ration 36.  62 

Period  3,  protein  ration 36.  25 

From  the  middle  of  period  1  to  the  middle  of  period  3  was  78  days, 
so  that  the  average  daily  falling  off  in  the  yield  of  milk  solids  was 
0.8904  gram,  and  for  the  40.5  days  between  period  1  and  period  2 
amounted  to  36.08  grams.  Morgen  therefore  makes  the  following 
comparison  of  the  yields  of  milk  solids: 

Grams. 

Period  1 t 105.  70 

Period  2:  Grams. 

Observed 36.  62 

Correction 36.  08 

Computed 72.  70 

Period  3: 

Observed 36.  25 

Correction 69.  45 

Computed 105.  70 

i  Morgen,  A.,  Beger,  C.,  and  NVesthausser,  F.  Untersitchungeniiberden  Einflussdernicht-eiweissartigen 
Stickstoffverbindungen  der  Futtennittel  auf  die  Milchproduktion.  Die  landwirtschaftiichen  Versuchs- 
Stationen,  Band  65,  Heft  5-6,  pp.  313-440.  Berlin,  1900-7. 


EFFECT  ON  TOTAL  PRODUCTION. 


39 


and  computes  that  the  effect  of  the  extract  ration  was  72. 70-=- 105.70  = 
08.8  per  cent  of  that  of  the  protein  ration.  The  assumption  under- 
lying sucli  a  correction  for  the  advance  of  lactation,  however,  is  that 
if  the  feed  had  been  unchanged  the  falling  off  in  yield  would  have 
been  proportional  to  the  time.  In  this  case,  therefore,  the  falling 
off  up  to  the  middle  of  period  2  would  have  been,  as  computed, 
30.08  grams,  and  consequently  the  }rield  of  milk  solids  on  an  un- 
changed ration  would  have  been  105.70  — 30. 08  =  09. (52  grains,  so  that 
we  may  make  the  following  comparison: 


Periods. 

Observed 
yield. 

Computed 
yield. 

Observed 
in  per- 
centage of 
computed. 

1  

Grams. 
105.  70 

Grams. 

]>tr  cent. 

3li  <>2 

1.9  (>'> 

5°  til 

3 

3(1  25 

Morgen's  method  of  computation,  in  other  words,  adds  the  same 
correction  to  two  unequal  quantities;  and  therefore,  while  the  differ- 
ence between  the  two  is  unaffected,  the  ratio  between  them  is  dis- 
torted in  favor  of  the  smaller  number. 

In  the  experiments  of  1907  the  basal  rations  contained  approxi- 
mately 2.5  kilograms  of  digestible  protein  per  1,000  kilograms  live 
weight,  of  which  approximately  0.9  kilogram  was  replaced  by  the  non- 
protein  of  malt  sprouts  extract.  The  following  table  shows  the  pro- 
duction of  milk  solids  and  of  milk  protein  expressed  as  a  percentage  of 
the  amount  which  it  is  computed  would  have  been  produced  had  the 
protein  ration  been  continued  unchanged,  the  computation  being 
made  in  the  manner  just  indicated.1 


1  In  certain  of  the  experiments  only  a  three-fourths  ration  could  be  fed  in  the  nonprotein  periods,  and 
corresponding  periods  were  introduced  in  which  three-fourths  of  the  normal  piotein  ration  was  fed.  In 
these  cases  the  results  have  been  computed  on  the  assumption  that  the  rate  of  decrease  in  milk  production 
would  have  been  the  same  as  was  actually  observed  between  the  two  full  protein  rations.  For  example, 
in  case  of  sheep  13  (loc.  cit.,  p.  402)  the  following  results  were  obtained: 


Milk 
solids. 


I'er  cent. 

Correct  ion  ( period  3-2) 22.  s"> 

Observed  yield  in  period  3  on  three-fourths  protein  ration 4ii.  47 


Computed  yield  in  period  2  on  three-fourths  protein  ration !        ti'J.32 

Observe-!  yield  in  period  2 !        40.  78 

Observed  in  percentage  of  computed I        58. 84 


Milk 
protein. 


I'er  cent. 
1.1/2 
2. 54 


3. 5(1 

2.29 

04.33 


40          NUTRITIVE   VALUE    OF    NONPROTEIN    OF    FEEDING   STUFFS. 
Yield  in  per  cent  of  yield  in  protein  periods — Morgen's  experiments  of  1907. 


Items. 

Milk 
solids. 

Milk 
protein. 

Malt  sprouts  extract  periods: 
Sheep  13  

Per  cent. 
58  84 

Per  cent. 
64  33 

Sheep  22  

84.38 

83  58 

Sheep  25 

75  38 

74  02 

Sheep  27... 

58.07 

54  72 

Sheep  27  (grass  extract) 

75  48 

65  57 

Sheep  30  

71.52 

71.16 

Sheep  32  

69.00 

67  76 

Sheep  34  

61.44 

59.76 

Average  of  percentages  

69.  26 

67  09 

Carbohydrate  periods: 
Sheep  22  

74.49 

73.71 

Sheep  27                                        .... 

59  12 

55  56 

Sheep  30  

83.58 

83  59 

Sheep  32  

01.62 

57.99 

Sheep  34  

52.12 

52.49 

Average  of  percentages                       

(>(i  19 

64  67 

In  general,  the  relative  yield  in  the  malt  sprouts  extract  periods 
is  somewhat  greater  than  that  obtained  from  a  corresponding  quan- 
tity of  carbohydrates,  although  there  are  individual  exceptions.  Ap- 
parently the  nonprotein,  while  greatly  inferior  to  protein,  had  a 
somewhat  greater  nutritive  value  than  the  carbohydrates. 

In  the  experiments  of  1908  the  basal  ration  contained  2.3  kilograms 
digestible  protein  per  thousand  live  weight.  In  the  various  periods 
either  28  per  cent  or  44  per  cent  of  this  protein  was  replaced  by  non- 
protein  derived  from  various  sources,  viz,  from  malt  sprouts  extract, 
grass  extract,  mangel  extract,  ammonium  salts,  and  asparagin,  while 
six  carbohydrate  periods  were  also  introduced.  The  relative  yields, 
computed  as  in  the  preceding  case,  using  the  yield  in  periods  1  and  5 
on  the  protein  ration  as  the  basis  of  computation,  were  as  follows: 

Yield  in  per  cent  of  yield  in  protein  periods    -Morgens  experiments  of  1908. 


Items. 

Percent- 
age of 
protein 
replaced. 

Milk 
solids. 

Milk 
protein. 

Malt  sprouts  extract: 
Sheep  13  . 

44 

Per  cent. 
52.  61 

Per  cent. 
62.40 

Sheep  22  

44 

79.  67 

79.97 

Sheep  27 

28 

67.44 

70.55 

Sheep  30 

44 

55.  91 

55.56 

Sheep  32  

44 

63.  71 

64.  63 

Sheep  33 

44 

48.57 

48.70 

Sheep  42  

28 

51.92 

52.74 

Goat  53  

28 

82.26 

85.71 

Average  of  percentages  

62.  76 

65.03 

Grass  extract: 
Sheep  49  

28 

53.08 

46.  77 

Goat  31 

28 

84.39 

82.87 

Goat  38  ....                                                                             

28 

73.72 

62.  86 

Goat  41  

28 

54.51 

48.28 

Goat  45  ...                                                                                       

28 

62.  92 

53.  62 

Goat  52  

28 

09.  05 

57.49 

Goat  53  ...                                                                             

28 

85.71 

89.18 

Average  of  percentages  

69.05 

63.01 

EFFECT  ON  TOTAL  PRODUCTION.  41 

Yield  in  per  cent  of  yield  in  protfin  period — Aforgen's  experiments  of  1908 — Continued. 


Items. 

Percent- 
age of 
protein 
replaced  . 

Milk           Milk- 
solids,      proteins. 

Mangel  extract: 
Sheep  31 

28 

28 
28 

Per  cent.    Per  cent. 
72.96             68.21 
59.08             51.74 
84.79 

Sheep  42 

Goat  28               .          

\veragc  of  percentages  .  . 

74.00            68.25 

Ammonium  salts: 
Sheep  34,  acetate     

44 

44 
44 

44 
44 
44 
44 

44 

28 
44 

28 
28 

102.  35            93.  75 
93.11             83.03 
107.  30            90.  33 
SO.  01             75.75 
78.12  1          74.25 
62.28  1          66.91 
86.  32             79.  50 
72.  97             72.  70 
69.  99            73.  77 
94.  69            86.  27 
81.13            85.11 
87.  34             82.  96 
66.13  j          70.51 

Sheep  37  acetate 

She»r>  48,  tartrate  

Sheep  48  acetate 

Sheep  49  acetate 

Sheep  50  acetate  

Goat  28,  acetate     

Goat  40  phosphate 

Goat  41  acetate 

Goat  45  acetate 

83.21             79.60 

Asparagin: 
Sheep  3.5 

44 
44 

SO.  ,50            81.82 
63.44            61.28 

Sheep  50 

71.97             71.55 
81.72             78.54 

Average  of  ammonium  sa 

Carbohydrates: 
Sheep  30                       

ts  and  asparagin 

44 
44 

54.  53            52.  74 
56.  96            57.  33 

Sheep  33         ...          

55.  75            55.  04 

Sheep  31                        

28 
28 
44 
28 

93.  63            95.  47 

S3.  78            82.  06 
95.24             94.70 
7'"  65             7li  3.5 

Sheep  as     

Sheep  40  

86  33             85  65 

Protein  withdrawn: 
Sheep  32            .             ... 



44 

63.  26              64.  25 

Averages: 
Malt  sprout-s  extr.ict 

62.76             65.03 
69  05              ai.Ol 

Grass  extract 

Mangel  extract   ..   . 

74.00             6S.25 
M  72             7s.  .r>4 

Ammonium  salts  and  a-spar 
Carbohydrates- 
Sheep 

.igin 

5.5  75              55.04 

S6  33              X5  (..') 

The  results  upon  the  individual  animals  were  more  or  less  variable, 
a  fact  probably  due  in  part  to  differences  in  the  order  of  (he  vari- 
ous periods  and  perhaps  to  individual  differences.  In  general,  the 
extracts  gave  results  fully  as  low  as  in  the  experiments  of  l'.)07.  hut  also 
somewhat  higher  than  those  obtained  in  the  carbohydrate  periods 
with  sheep.  The  results  with  goats  in  the  latter  periods  seem  excep- 
tional. On  the  other  hand,  the  relative  yield  upon  ammonium  salts 
and  asparagin  was  notably  greater  than  on  the  plant  extracts,  although 
falling  materially  short  of  that  obtained  with  protein. 

It  should  be  noted  that  the  low  value  of  the  extracts  as  compared 
with  ammonium  salts  may  be  due  to  a  small  extent  to  a  specific  effect 


42 


NUTRITIVE   VALUE    OF    NONPROTEIN    OF    FEEDING    STUFFS. 


of  these  materials  on  the  milk  production,  as  appears  from  the  results 
of  the  next  year. 

In  the  experiments  of  1909  the  basal  ration  contained  2.4  kilograms 
of  digestible  protein  per  thousand  live  weight.  In  eight  trials  63  per 
cent  of  this  was  replaced  by  ammonium  acetate  containing  an  equal 
amount  of  nitrogen.  In  the  other  trials  ammonium  acetate  and 
extracts  of  grass,  malt  sprouts,  and  dried  beet  pulp  were  simply  added 
to  the  basal  ration.  The  results,  computed  as  before,  are  contained 
in  the  following  table: 

Yield  in  per  cent  of  yield  in  protein  periods — Morgerts  experiments  of  1909. 


Items. 


Milk 
solids. 


Milk 
protein. 


Ammonium  acetate— substitution  experiments:  Per  cent.    Per  cent. 

Sheep  32 52. 89  54. 63 

Sheep  48 60. 68  58. 13 

Sheep  49 57. 68  56. 94 

Sheep  50 64. 85  61. 42 

Sheep  56 58. 96  59. 30 

Sheep  57 73. 50  75. 26 

Sheep  61 59. 69  64. 63 

[Goat  51] [88. 37]  [77. 58] 

Average  of  percentages  (omitting  goat  51) 61. 04  61. 47 

Ammonium  acetate— addition  experiments: 

Sheep  32 85. 49  91. 08 

Sheep  48 79. 44  74. 38 

Sheep  49 93. 57  91. 62 

Sheep  50 93. 06  89. 34 

Sheep  56 108. 44  102. 23 

Sheep  57  (period  3) 95. 39  99. 17 

Sheep  57  (period  4) 107. 55  105. 21 

Sheep  61 94. 29  92. 46 

[Goat  51] [144. 25]  [142. 20] 

Average  of  percentages  (omitting  goat  51) 94. 15  93. 19 

Grass  extract— addition  experiments: 

Sheep  35 85.33  82. 96 

Sheep  42 93. 77  85. 91 

Goat  45 93.57  90.07 

90. 89  80. 31 

Malt  sprouts  extract- -addition  experiments: 

Goat  38 93. 17  91. 25 

Goat  40 91. 50  85. 51 

Goat  52 92. 46  87. 07 

Average  of  percentages 92. 38  87. 94 

Beet-pulp  extract— addition  experiments: 

Sheep  35 86.87  84. 84 

Sheep42 80.91  73.21 

Goat  38 91. 66  89. 45 

Goat  40 95. 51  86. 23 

Goat  45  (period  3) 77. 60  75. 64 

Goat  45  (period  4) 77. 41  73. 55 

Goat  52 84. 56  83.  78 

Average  of  percentages 84. 93  80. 96 

Averages: 

Ammonium  acetate— substitution  experiments 61. 04  61. 47 

Ammonium  acetate— addition  experiments 94. 15  93. 19 

Grass  extract— addition  experiments 90. 89  86. 31 

Malt  sprouts  extract— addition  experiments 92. 38  87. 94 

Beet-pulp  extract— addition  experiments 84. 93  80. 96 


In  the  substitution  experiments  with  ammonium  acetate,  the  milk 
yield  fell  off  much  more  than  in  1908,  obviously  because  the  substitu- 


EFFECT  ON  TOTAL  PRODUCTION.  43 

tion  was  carried  much  further.  On  the  other  hand,  the  addition  of 
ammonium  salts  to  the  basal  ration  produced  practically  no  effect 
upon  the  yield,  the  small  differences  noted  being  scarcely  significant. 
The  addition  of  the  various  extracts  seems  to  have  caused  some 
decrease  in  the  yield,  which,  as  already  suggested,  may  indicate  a 
specific  effect,  but  one  which  is  not  great  enough  to  account  for  the 
falling  off  noted  in  the  substitution  experiments  of  the  previous  year. 

The  foregoing  results  fully  confirm  the  conclusions  drawn  from  a 
study  of  the  nitrogen  balances,  and  show  that  the  ammonium  salts, 
asparagin,  and  plant  extracts  all  seem  to  have  enabled  the  animals 
to  produce  a  greater  amount  of  milk  than  did  a  corresponding  amount 
of  carbohydrates.  WTith  the  plant  extracts  this  difference  is  com- 
paratively slight,  but  with  ammonium  acetate  and  asparagin  it  is 
quite  decided.  It  would  appear  as  if  these  latter  readily  soluble 
materials  are  more  easily  converted  into  protein  by  the  bacteria  of 
the  digestive  tract  than  are  the  diverse  nonprotein  substances  of 
plant  extracts. 

On  the  other  hand,  the  amount  of  nonprotein  nitrogen  thus  rendered 
available  was  relatively  small.  The  organism  reacted  to  the  replace- 
ment of  protein  by  ammonium  ssdts  chiefly  by  diminishing  the  amount 
of  milk  produced,  while  under  these  conditions  it  was  able  to  utilize 
that  portion  of  the  nonprotein  rendered  available  by  bacterial  action. 
When,  however,  the  protein  supply  was  reasonably  abundant,  the 
amount  which  may  have  been  formed  from  the  added  nonprotein 
under  those  circumstances  produced  no  perceptible  effect  upon  the 
milk  yield. 

These  relations  are  perhaps  most  apparent  in  the  case  of  the  four 
digestion  experiments  of  1909  in  which  the  protein  of  the  basal  ration 
was  replaced  by  ammonium  acetate  (p.  34).  If  we  compute  in  the 
same  manner  as  in  the  foregoing  cases  what  the  amount  of  nitrogen 
in  the  milk  yield  would  have  been  had  the  protein  ration  been  con- 
tinued, we  get  the  following  results: 

Influence  of  feed  protein  on  i/iclrl  of  milk  pro^in     Morgan's  experiments  of  19<>9. 

Yield  of  milk  protein. 

Items.  obw-rvetl     , 

for  non-     ,  (<""P"l':d 


Yield  of  nitrogen  in  milk:  '  Grams.     '  Grnmx. 

Sheep  48 4.  i:>  7. 14 

Sheep  49 :;.  r,i  t;.  34 

Sheep  50 3.  5.">  '.  5.  78 

Sheep  56 '  3. 19  5.  3S 


Average 3. 63  6. 16 


Average  available  protein  nitrogen  of  feed !  2.  7ii  i  13.28 


44          NUTRITIVE   VALUE    OF    NONPROTEIN    OF    FEEDING   STUFFS. 

On  the  protein  rations  the  supply  of  food  protein  was  sufficient  to 
cover  the  demand  for  maintenance,  the  gain  of  protein  by  the  body, 
and  the  production  of  protein  in  the  milk,  and  to  leave  an  average 
surplus  of  3.48  grams  nitrogen.  When,  however,  the  available  pro- 
tein supply  was  reduced  to  the  low  figure  of  2.76  grams  nitrogen,  or 
21  per  cent  of  the  previous  amount,  the  yield  by  the  animals  was 
reduced  in  the  case  of  the  milk  solids  by  39  per  cent  and  in  the  case 
of  the  milk  protein  by  41  per  cent.  This  large  falling  off  makes  it 
evident  that  the  protein  supply  was  the  limiting  factor  of  milk  pro- 
duction in  these  periods.  Under  these  conditions  of  limited  protein 
supply,  however,  the  nonprotein  nitrogen  of  the  feed  was  utilized  to  a 
certain  extent  as  is  shown  by  the  nitrogen  balances,  so  that  the  falfing 
off  in  the  yield  of  milk  was  not  proportional  to  the  reduction  in  the 
protein  supply. 

DIRECT    UTILIZATION    OF    AMMONIUM    SALTS. 

It  will  not  have  escaped  notice  that  the  evidence  of  the  utilization 
of  nonprotein  by  means  of  the  formation  of  bacterial  protein  which  is 
furnished  by  the  foregoing  experiments  is  indirect.  Since  it  has  not 
been  satisfactorily  shown  that  carnivora  or  omnivora  can  utilize  non- 
protein  as  a  source  of  protein,  it  is  concluded  that  the  opposite  results 
with  herbivora  can  not  be  ascribed  to  a  synthetic  production  of  pro- 
tein in  the  processes  of  metabolism,  but  must  be  due  to  some  other 
cause,  the  formation  of  bacterial  protein  appearing  the  most  probable 
one. 

Moreover,  the  most  decided  nutritive  effect  is  obtained  with 
ammonium  salts,  i.  e.,  precisely  those  compounds  which  seem  least 
likely  to  be  subject  to  metabolic  synthesis.  In  this  connection, 
however,  attention  should  be  called  to  two  recent  papers. 

Knoop1  claims  to  have  established  the  theoretical  possibility  of  a 
formation  of  amino  acids  in  the  body  of  the  dog  from  ammonia  and 
nonnitrogenous  substances.  According  to  him,  the  deamidization 
of  the  amino  acids  resulting  from  protein  cleavage  in  metabolism  is 
a  process  of  oxidation,  giving  rise  to  the  -corresponding  keto  and 
oxy  acids  and  ammonia.  This  change  he  regards  as  a  reversible 
reaction  and  assumes  the  formation  of  hypothetical  intermediate 

products  of  the  type 

OH 

-COOH 


from  which  either  ammonia  or  water  may  be  split  off  according  to 
the  direction  of  the  reaction. 

1  Knoop,  F.  Uber  den  physiologischen  Abbau  der  Siiuren  und  die  Synthese  einiger  Aminosauren  im 
Tierkorpcr.  Zeitschrift  fiir  physiologische  Cheinie,  Band  67,  Heft  6,  pp.  289-502.  Strassburg,  1910.  See 
p.  489. 


DIRECT   UTILIZATION    OF   AMMONIUM    HALTS.  45 

It  does  not  appear  that  Knoop  actually  experimented  with  ammo- 
nium salts,  but  Embden  and  Schmitz1  in  perfusion  experiments  on 
the  liver  have  observed  the  formation  of  tyrosin,  phenylalanin,  and 
alanin,  and  probably  of  leucin,  when  the  ammonium  salts  of  corre- 
sponding acids  were  added  to  the  perfused  blood.  The  yield  of 
alanin  was  especially  large  from  pyruvic  acid  and  less  so  from  lactic 
acid,  which  corresponds  with  Knoop's  view.  When  a  liver  rich  in 
glycogen  was  perfused  with  blood  containing  ammonium  chlorid, 
alanin  was  also  obtained.  This  fact  the  authors  explain  as  due  to  a 
formation  of  lactic  acid  from  liver  carbohydrate,  and  regard  it  as 
showing  the  possibility  of  the  formation  of  an  amino  acid  from 
ammonia  and  a  carbohydrate.  Even  if  the  foregoing  results  are  con- 
firmed by  further  investigation,  their  significance  for  questions  of 
nutrition  may  perhaps  be  questioned;  but,  nevertheless,  the  possibility 
of  a  synthesis  of  ammonia  to  amino  acids,  and  thence  to  protein,  by 
higher  animals  as  well  as  by  lower,  should  not  be  lost  sight  of. 


The  results  recorded  in  the  foregoing  pages  ma\*  be  briefly  summa- 
rized as  follows: 

1.  Arnino  acids  and  amids,  which  ordinarily  constitute  the  larger 
part  of  the  nonprotein  of  vegetable  substances,  are  katabolized  in  the 
animal  body,  their  nitrogen  appearing  in  the  urine. 

2.  In  carnivora  and  omnivora  neither  the  single  substances  of  the 
foregoing  groups  nor  the  mixtures  of  them  contained  in  plant  ex- 
tracts have  been  shown  to  be  capable  of  performing  the  functions  of 
protein. 

3.  In  ruminants  a  conversion  of  nonprotein  into  protein  appears 
to  be  effected  by  the  micro-organisms  of  the  digestive  tract.     The 
extent  of  this  conversion  appears  to  be  relatively  greater  in  the  case 
of  ammonium  salts  and  asparagin  than  in  that  of  vegetable  extracts. 

4.  The  protein  formed  thus  from  nonprotein  scorns  to  t>o  digested 
subsequently.     The  apparent  formation   of  indigestible   protein   ob- 
served by  some  investigators  appears  to  be  due  to  an  increase  in  the 
metabolic  products  contained  in  the  feces,  caused  by  a  specific  action 
of  the  extracts  upon  the  digestive  tract. 

5.  By  means  of  its  conversion  into  bacterial  protein,  the  nonpro- 
tein of  feeds  may  serve  indirectly  for  maintenance  and  also  as  a 
source  of  protein  for  milk,  and  probably  for  growth,  in  rations  defi- 
cient in  protein. 

6.  The  limiting  factor  in  the  indirect  utilization  of  the  nonprotein 
of  the  feed  appears  to  be  the  extent  to  which  it  can  be  converted 
into  protein  in  the  digestive  tract  rather  than  any  inferior  nutritive 

1  Embden,  Oustav,  and  Schmitz,  Ernst.     Uber  synthetische  Bildungvon  Aminosiiuren  in  der  Leber. 
Biochemische  Zeitschrift,  Band  29,  Heft  6,  pp.  423-428.     Berlin,  1910. 


46         NUTRITIVE  VALUE   OF    NONPROTEIN   OP   FEEDING   STUFFS. 

value  of  the  protein  thus  formed  as  compared  with  that  originally 
present  in  the  feed. 

7.  The  nonproteins  are  much  inferior  to  the  proteins  in  nutritive 
value  for  productive  feeding.     The  prime  effect  of  a  substitution  of 
nonproteins  for  proteins  in  the  ration  is  a  very  marked  falling  off 
in  the  production.     The   indirect   utilization  of  nonprotein  simply 
serves  to  prevent  this  decrease  from  becoming  as  great  as  it  other- 
wise would,  and  so  in  case  of  need  to  compensate  partially  for  a  defi- 
ciency of  protein.     On  the  other  hand,  with  a  reasonable  supply  of 
digestible  protein  the  addition  of  nonprotein  usually  fails  to  increase 
the  production  of  nitrogenous  matter. 

8.  Recent  experiments  raise  the  question  of  the  possibility  of  a 
direct  utilization  of  ammonia  as  a  source  of  protein  by  the  higher 
animals. 

CONCLUSIONS. 

If  the  foregoing  summary  may  be  regarded  as  expressing  with 
substantial  accuracy  the  present  state  of  our  knowledge  regarding 
the  behavior  of  nonprotein  in  the  animal  body,  what  conclusions  can 
be  drawn  from  the  facts  there  set  forth  as  to  the  value  to  be  assigned 
to  this  group  in  the  computation  of  rations  for  farm  animals  ? 

VALUE    FOR    MAINTENANCE    OF   PROTEIN   TISSUES. 

It  appears  to  be  well  established  that  nonprotein  may  be  of  equal 
value  with  protein  for  the  maintenance  of  the  protein  tissues  of  the 
body,  so  far  at  least  as  this  can  be  determined  from  the  nitrogen 
balance. 

Kellner's  experiments  on  lambs  (pp.  30-32)  show  qualitatively  that 
ammonium  salts  and  asparagin  may  perform  the  functions  of  pro- 
tein in  this  respect,  but  they  were  present  in  excess  and  but  a 
comparatively  small  proportion  of  them  was  utilized.  In  the  experi- 
ments on  cows  reported  by  the  Danish  investigators  (pp.  36-37) 
little  or  no  protein  was  left  after  the  demands  of  milk  production 
were  met,  and  the  maintenance  function  must  have  been  supported 
almost  wholly  by  the  nonprotein.  Even  assuming  a  minimum  value 
for  the  maintenance  requirement,  there  are  a  number  of  cases  in 
which  nearly  or  quite  100  per  cent  of  the  nonprotein  appears  to 
have  been  thus  utilized,  while  in  Kellner's  experiment  (p.  35)  the 
available  feed  protein  did  not  even  equal  that  produced  in  the  milk. 
In  these  cases  at  least,  it  seems  necessary  to  conclude  that  a  unit  of 
nonprotein  nitrogen  in  the  ration  was  of  equal  value  with  a  unit  of 
protein  nitrogen.  Morgen's  experimental  results  (pp.  32-35)  occupy 
in  this  respect  an  intermediate  position.  They  show  that  the  non- 
protein  must  have  served  for  either  maintenance  or  production,  but 
a  relatively  small  proportion  of  it  (15  to  41  per  cent)  was  utilized  in 
this  way. 


VALUE   FOR    MAINTENANCE   AND    PRODUCTION.  47 

VALUE    FOR    PRODUCTION. 

With  the  exception  of  Kellner's  and  Morgen's  experiments  with 
ammonium  acetate,  there  is  as  yet  no  positive  evidence  that  non- 
protein  can  replace  protein  for  productive  purposes,  and  ammonium 
salts  do  not  occur  in  ordinary  feeding  stuffs  in  any  considerable 
amount.  In  Morgen's  experiments  with  plant  extracts  the  supply  of 
protein  was  more  than  sufficient  in  all  cases  to  meet  the  demands  of 
the  diminished  milk  production.  In  the  Danish  experiments,  with 
a  relatively  heavier  milk  production  in  the  low  protein  periods,  the 
limit  was  more  nearly  reached,  but  there  can  hardly  be  said  to  have 
been  a  significant  deficit  of  protein  in  any  instance. 

As  was  stated  on  pages  32  and  35,  it  appears  to  the  writer  probable 
that  the  limiting  factor  in  these  cases  was  the  extent  to  which  the 
bacterial  synthesis  of  protein  was  carried,  rather  than  an  inferiority 
in  the  nutritive  value  of  the  product.  But  however  this  may  be,  the 
practical  result,  from  the  standpoint  of  the  computation  of  rations, 
is  as  if  the  nonprotein  contained  in  rations  such  as  are  ordinarily  fed 
may  serve  for  maintenance  but  not  for  production.  Whether  a  more 
extensive  substitution  of  this  type  of  nonprotein  in  place  of  protein 
would  yield  a  different  result  can  of  course  be  decided  only  by  experi- 
ment. It  may  be  remarked,  however,  that  the  proportion  of  non- 
protein  to  protein  in  the  recorded  experiments  appears  to  be  as  groat 
as  it  is  likely  to  be  in  any  ordinary  ration,  and,  pending  further  evi- 
dence, it  would  seem  to  be  the  part  of  safety  to  consider  that  ordi- 
narily not  enough  of  the  nonprotein  is  converted  into  protein  (by 
bacterial  action  or  otherwise)  to  make  it  of  any  material  significance 
for  the  production  of  milk  protein  (and  probably,  therefore,  of  pro- 
tein tissue). 

THE    COMPUTATION    OF    RATION'S. 

If,  however,  the  nonprotein  is  to  be  regarded  as  of  full  value  for 
maintenance  but  as  practically  valueless  for  production,  an  undesir- 
able complication  is  introduced  into  the  computation  of  rations.  The 
value  of  a  feeding  stufT  (as  regards  protein)  in  a  maintenance  ration 
would  be  measured  by  its  total  nitrogen  (''crude  protein"),  wbile  the 
corresponding  value  of  the  same  feeding  stuff  for  productive  purposes 
would  be  measured  by  its  protein  nitrogen. 

But  a  considerable  part  of  every  productive  ration  serves  for  the 
maintenance  of  the  animal.  A  part  of  the  protein  requirement, 
therefore,  might  be  met  indifferently  by  either  protein  or  nonprotein, 
while  for  the  remainder  only  protein  would  serve.  For  example, 
suppose  a  dairy  cow  to  require  per  day  0.5  pound  protein  for  main- 
tenance and  1.75  pounds  for  the  production  of  35  pounds  of  average 
milk.  She  must  be  supplied  with  a  ration  containing  a  total  of  2.25 


48         NUTRITIVE  VALUE   OP    NONPROTEIN   OF   FEEDING  STUFFS. 

pounds  of  digestible  nitrogenous  matter,  in  which,  however,  the  non- 
protein  may  vary  from  0  to  0.5  pound,  but  may  not  exceed  the  latter 
limit.  If,  then,  the  "crude"  protein  (NX6.25)  of  the  ration  is  made 
the  basis  of  the  computation  and  a  ration  is  formulated  supplying 
the  necessary  2.15  pounds  of  digestible  nitrogenous  matter,  a  sup- 
plementary calculation  would  be  required  to  determine  whether  or 
not  the  limit  for  nonprotein  has  been  exceeded.  Such  a  calculation, 
while  it  might  signify  little  to  the  expert,  would  constitute  an  addi- 
tional difficulty  in  the  way  of  teaching  the  computation  of  rations  to 
the  practical  farmer,  who  usually  finds  the  subject  sufficiently  unfa- 
miliar and  complicated  even  when  presented  in  the  simplest  possible 
way. 

It  is  to  be  remarked  in  the  first  place  that,  so  far  as  appears  from 
the  results  cited  in  the  foregoing  pages,  the  nonprotein  of  feeding 
stuffs  is  available  for  the  maintenance  of  ruminants  only,  while  in 
the  case  of  swine  and  probably  of  horses  only  the  protein  can  be  used 
for  this  purpose.  In  the  case  of  the  two  latter  species,  therefore,  it 
is  evident  that  the  digestible  protein  should  be  made  the  basis  of  the 
computation.  Ultimately,  of  course,  we  should  have  separate  tables 
of  feed  values  for  these  animals,  since  their  digestive  capacity  is  in 
some  respects  materially  different  from  that  of  ruminants.  For  the 
present,  or  as  long  as  we  continue  to  use  a  single  table  for  all  species 
of  domestic  animals,  it  seems  undesirable  to  complicate  the  calcula- 
tion in  the  case  of  ruminants  by  introducing  the  nonprotein  into  the 
calculation.  Pending  further  investigation,  therefore,  it  would 
appear  to  be  the  wisest  course  to  continue  to  use  ordinarily  the 
digestible  true  protein  as  the  basis  of  computing  rations,  ignoring 
the  nonprotein.  While  doing  this,  however,  it  should  be  appreciated 
that  rations  thus  computed  will  be  likely  to  be  unnecessarily  high  in 
protein,  especially  if  composed  largely  of  feeding  stuffs  rich  in  non- 
protein,  such  as  roots,  silage,  and  green  forage.  This  will  be  par- 
ticularly the  case  when  the  protein  requirement  for  maintenance 
constitutes  a  large  proportion  of  the  total  protein  requirement,  as, 
for  example,  in  working  horses  or  in  mature^attening  animals;  while, 
on  the  other  hand,  the  error  will  be  least  with  growing  stock  or  good 
dairy  cows  where  the  productive  quota  is  large  as  compared  with  the 
maintenance  requirement. 

If  it  is  desired  to  make  the  computation  more  accurate  in  the  case 
of  ruminants,  so  as  to  avoid  any  excess  of  the  relatively  costly  protein, 
it  would  appear  that  this  end  might  be  most  simply  reached  by  the 
method  about  to  be  suggested.  This  consists  in  formulating  sep- 
arately the  protein  requirement  for  maintenance  and  for  productive 
purposes,  computing  a  ration  which  shall  supply  sufficient  true  protein 
to  meet  the  requirement  for  production,  and  then  computing  whether 
this  ration  contains  sufficient  nonprotein  to  cover  the  maintenance 


THE   COMPUTATION    OF    RATIONS. 


49 


requirement.1  Suppose,  for  example,  it  is  desired  to  compute  a  ration 
for  a  1,000-pound  cow  producing  daily  35  pounds  of  average  milk. 
Using  for  illustration  the  requirements  formulated  by  the  writer,2 
the  ration  of  the  animal  should  contain,  for  milk,  1.6  pounds  protein 
and  9.6  therms  energy  value;  for  maintenance,  0.5  pound  protein  or 
nonprotein,  and  6  therms  energy  value. 

Disregarding  in  the  first  instance  the  nonprotein  requirement,  we 
may  compute  the  following  ration  which  supplies  the  necessary 
amounts  of  true  protein  and  of  energy : 


Ration. 

Dry 
matter. 

Digesti- 
ble pro- 
tein. 

Non- 
protein. 

Energy. 

Silage,  40  pounds  

rounds. 
10.2 

Pounds. 
0.26 

Pound. 
0.21 

Therms. 
6.64 

Clover  hav,  15  pounds. 

12.7 

.80 

.30 

5.21 

Com  chop,  5  pounds  

4.2 

.22 

.02 

3.60 

Cottonseed  meal,  1  pound  

.9 

.35 

.02 

.84 

28.0 

1.63 

.55 

16.29 

A  supplementary  calculation  shows  that  the  foregoing  ration  would 
also  contain  0.55  pound  nonprotein,  the  amount  supplied  by  each  feed- 
ing stuff  being  included  for  convenience  in  the  foregoing  table.  The 
ration  as  computed  thus  proves  to  contain  a  slight  excess  of  nonprotein 
over  the  estimated  maintenance  requirement,  and  may  therefore  be 
regarded  as  adequate,  while  if  the  total  requirement  for  nitrogenous 
matter  had  been  supplied  by  true  protein  it  would  have  been  necessary 
to  use  at  least  H  pounds  more  of  cottonseed  meal  in  the  ration. 
\Yhile  this  method  of  computation  adds  slightly  to  the  labor  of  com- 
puting rations  for  ruminants,  it  has  the  advantage  of  tending  to  econ- 
omy in  the  use  of  protein  concentrates,  a  thing  which  appears  desira- 
ble since  these  are  usually  the  expensive  ingredients  of  the  ration  and 
since  recent  investigation  indicates  strongly  that  the  protein  require- 
ments of  animals  have  been  more  or  less  exaggerated  in  the  current 
feeding  standards. 


1  For  this  purpose  it  would  of  course  be  necessary  that  (he  table  used  should  show  the  percentage  of  non- 
protein  in  the  feeding  stuffs  in  question. 

J  Armsby,  Henry  P.  The  computation  of  nit  ions  for  farm  animals  by  the  use  of  energy  values.  I  .  S. 
Department  of  Agriculture,  Farmers'  Hulleiin  :>tr>.  Washington,  1909.  See  p.  r.i. 


o 


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